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Environmental Water Requirements to Maintain of National and International Importance ENVIRONMENTAL FLOWS INITIATIVE TECHNICAL REPORT REPORT NUMBER 1 Environmental Water Requirements to Maintain Wetlands of National and International Importance

A Commonwealth Government Initiative National River Health Program healthy rivers living rivers rivers for life

ENVIRONMENTAL FLOWS INITIATIVE TECHNICAL REPORT REPORT NUMBER 1 Environmental Water Requirements to Maintain Wetlands of National and International Importance

Authors: Jenny Davis, Ray Froend, David Hamilton, Pierre Horwitz, Arthur McComb, Carolyn Oldham and Deb Thomas

A Commonwealth Government Initiative Published By: Environment GPO Box 787 CANBERRA ACT 2601

Authors: J Davis, R Froend, D Hamilton, P Horwitz, A McComb, C Oldham and D Thomas School of Murdoch University South St, Murdoch WA 6150

Copyright:  Commonwealth of Australia, November 2001

This work is copyright. Information contained in this publication may be copied or reproduced for study, research, information, or educational purposes, subject to inclusion of an acknowledgment of the source. Requests and inquiries concerning reproduction and rights should be addressed to:

Assistant Secretary Water Branch Environment Australia GPO Box 787 Canberra ACT 2601

Disclaimer: The views and opinions expressed in this publication are those of the authors and do not necessarily reflect those of the Commonwealth Government or the Minister for the Environment and Heritage.

While reasonable efforts have been made to ensure that the contents of this publication are factually correct, the Commonwealth does not accept responsibility for the accuracy or completeness of the contents, and shall not be liable for any loss or damage that may be occasioned directly or indirectly through the use of, or reliance on, the contents of this publication.

The information contained in this work has been published by Environment Australia to help develop community, industry and management expertise in sustainable water resources management and raise awareness of river health issues and the needs of our rivers. The Commonwealth recommends that readers exercise their own skill and care with respect to their use of the material published in this report and that users carefully evaluate the accuracy, currency, completeness and relevance of the material for their purposes.

Citation: For bibliographic purposes this report may be cited as: Davis, JA., Froend, RH., Hamilton, DP., Horwitz, P., McComb, AJ., Oldham, CE., Environmental Water Requirements to Maintain Wetlands of National and International Importance (2001), Environmental Flows Initiative Technical Report Number 1, Commonwealth of Australia, Canberra.

ISBN: 0642547688

Information: For additional information about this publication, please contact the author(s). Alternatively, you can contact the Community Information Unit of Environment Australia on toll free 1800 803 772.

Cover Photo credits: Main image: Caulder , Lakefield National Park ( PD Canty). Top thumbnail image: Nameless creek in Gulf of Carpenteria region ( PD Canty). Middle thumbnail image: Creek sampling ( Commonwealth of Australia). Bottom thumbnail image: Water reflections in Cathedral Chasm ( PD Canty).

EXECUTIVE SUMMARY

A wide range of human impacts have resulted in changes to water regimes throughout Australia. Regional issues affecting wetland water regimes include river regulation, diversion and abstraction in the Murray- Darling Basin, excessive inundation in the Western Australian wheatbelt and parts of the coastal , and aquifer draw-down in the Great Artesian Basin. Specific local impacts which affect wetland water regimes include hydrological alterations associated with urban and agricultural development. Increasingly, decisions must be made regarding the amount, duration and timing of water required to restore aspects of wetland structure and function or prevent further degradation.

In both Australia and overseas, environmental water allocation has focussed on rivers. Initially the prime motivating concern was improving habitat and meeting fish passage requirements. Later, broader issues were considered, such as the maintenance of ecosystem processes. Where wetlands are associated with river systems some attempt has been made to incorporate them into the environmental flow allocation process for the river.

Wetland environmental water allocation differs from that of rivers in several aspects. Variability of water quantity in wetlands is associated with the presence of habitats of different depths. These habitats are characterised by particular plant and waterbird communities. There is generally a close connection between water quantity and the spatial extent of wetland habitat. While the determination of environmental flows for rivers generally occurs at large scales, with the examination of entire river

ENVIRONMENTAL WATER REQUIREMENTS FOR WETLANDS V

systems, environmental water allocations for wetlands may sometimes occur at much smaller spatial scales.

Management of environmental water allocation for wetlands in Australia has mainly focused on wetland systems where the is altered by water extraction, however the issue of drainage into wetlands and inundation as a result of rising water tables also needs to be addessed. That is, wetlands can have ‘too much water’ as well as ‘too little water’.

Water regimes of the following wetlands are managed to meet environmental and other objectives. The history of this management is summarised.

Macquarie (north-west NSW).

Lower Gwydir Basin Wetlands (northern tablelands of NSW).

Kerang ().

Wetlands of the Lachlan River Valley (southern inland NSW).

Lake Merreti and Lake Woolpolool (Chowilla Floodplain, SA)

-Millewa (Victoria-NSW border)

Lakes of the Gnangara Mound on the (WA)

Twin , the Swan Coastal Plain (WA)

Measures aimed at protecting the water resources of the Great Artesian Basin are also briefly presented. These measures have the effect of protecting mound springs, although generally they are designed to protect the water resource for consumptive use.

Approaches to determining the environmental water requirements of wetlands can be divided into hydrology-driven and -driven

VI ENVIRONMENTAL WATER REQUIREMENTS FOR WETLANDS

methods. Hydrology-driven approaches involve first the description then the restoration or partial restoration of the historic (pre-disturbance) water regime of the wetland. It is assumed that the biota is adapted to the pre- disturbance water regime and that the restoration of this regime will result in a healthy ecosystem. Ecology-driven approaches involve the determination of the water regime requirements of the existing or preferred biota, and the provision of that regime. Ecology-driven approaches may lead to more defensible allocations than those determined by hydrology- driven approaches. Strengths and weaknesses of both hydrology- and ecology-driven approaches were examined through the use of case studies.

Invasive species are frequently favoured by alterations to water regimes, although in many instances other factors will also be implicated, for example, disturbance or grazing. Ecology-driven approaches to environmental water allocations may include water management strategies to control invasive species. They may also incorporate measures to protect or communities.

A comprehensive ecology-driven method was used for the determination of Environmental Water Requirements and Environmental Water Allocations for the groundwater-fed wetlands of the Gnangara Mound on the Swan Coastal Plain, WA. The water regimes of these wetlands are threatened by groundwater extraction. The hydrology of the wetlands and the water requirements of the wetland vegetation, aquatic invertebrates and waterbirds were examined in targeted research programs. The water regime requirements of vegetation were first examined, with an objective of maintaining the existing distributions. These requirements were then compared with the requirements of aquatic invertebrates and waterbirds, for the determination of Environmental Water Requirements. Individual

ENVIRONMENTAL WATER REQUIREMENTS FOR WETLANDS VII

objectives and Environmental Water Requirements were set for each wetland, reflecting their particular environmental values. This approach has similarities with a methodology developed for the determination of water requirements of the vegetation of floodplain wetlands by Roberts et al. (2000). It differs in that the requirements of wetland fauna were examined as well as those of vegetation.

In practice, determinations of environmental water allocations for wetlands generally depend on an assessment of pre-development and current water regimes, and the effects of altered hydrology on wetland vegetation, due to limitations of knowledge regarding the water requirements of biota. The use of objectives based on identified values and the requirements of wetland biota is likely to provide a high level of defensibility for decisions regarding environmental water allocations.

Australian wetlands are generally characterised by extremely variable water regimes. Natural variations in climate result in variable water regimes both within and between years. Incorporating this variability into the managed water regime is likely to be of greater importance than the maintenance of minimum water levels. Mound spring wetlands are an exception as they are characterised by stable, permanent water regimes.

This report describes a framework for determining environmental water allocations for wetlands of international and national significance. It incorporates the determination of management objectives based on both hydrological and ecological characteristics of the wetland and the uses, values and threats associated with it. Relationships between the biota and water regime are used to determine the water allocation required to achieve the management objectives. These are refined by using conceptual

VIII ENVIRONMENTAL WATER REQUIREMENTS FOR WETLANDS

modelling to examine various scenarios and by considering trade-offs between different values and uses.

The framework was trialed on four wetlands representing different wetland types. These were:

Thomsons Lake, WA (groundwater dominated). The framework was trialed in most detail at this wetland because of the extensive data available.

Bool and Hacks , SA (floodplain wetland affected by an irrigation scheme).

Lower , NSW (a terminal riverine wetland).

Boggomoss Springs, Qld (artesian springs).

The outcomes of the trials are summarised by the following information. At Thomsons Lake, a Ramsar-listed wetland in south-, water regime very much influences the extent of shallow water and fringing vegetation, which is important for waterbirds. The water regime is threatened by both groundwater extraction and rising water tables resulting from clearing; these impacts mitigate each other. The water regime of Bool and Hacks Lagoons has been affected by an irrigation scheme, and is now deeper and more permanent. This has adversely affected the health of a stand of Melaleuca. The Gwydir wetlands are terminal riverine wetlands affected by upstream abstraction of water for irrigation and other consumptive uses. This has resulted in an overall reduction in water quantity in the wetlands, leading to a change in plant community composition. Boggomoss Springs are artesian springs threatened by aquifer draw-down. Some of the springs are also threatened by flooding from the proposed Nathan Dam.

ENVIRONMENTAL WATER REQUIREMENTS FOR WETLANDS IX

1. Characterise wetland in terms of 2. Identify • hydrology • uses • ecology • values • threats

3. Determine MANAGEMENT OBJECTIVES

4. Describe relationships between biota and water regime, focusing on relationships related to objectives

5. Determine the desired water regime to fulfil management objectives.

6. Refine desired water regime by examining various scenarios using conceptual modelling. Resolve trade-offs between all values and uses. Finalise the water regime requirements

8. Determine means of achieving the desired water regime 7. Set performance indicators in relation to biota.

9. Prescribe environmental water allocations to achieve the desired water regime

10. Implementation

Compare 11. Monitoring Compare against against performance environmental indicators water ll ti Results from Results from biological hydrological monitoring monitoring

X ENVIRONMENTAL WATER REQUIREMENTS FOR WETLANDS

FRAMEWORK FOR DETERMINING ENVIRONMENTAL WATER ALLOCATIONS FOR WETLANDS OF INTERNATIONAL AND NATIONAL SIGNIFICANCE

The presence of physical structures such as dams, weirs, irrigation channels and levee banks may limit the ability to deliver environmental water allocations. Other limitations are related to the relatively large scale of problems, such as rising water tables, and the consumptive demand for water. The ability to determine appropriate water allocations is frequently limited by knowledge regarding both the pre-development water regime and the requirements of biota. Significant opportunities for environmental water allocations exist where abstraction is characterised by a large amount of wastage (eg, unregulated artesian bores) and in isolated wetlands where water regimes may sometimes be manipulated relatively easily.

Acknowledgements Dr Chris Gippel critically reviewed the manuscript at several stages during its preparation and provided a number of unpublished reports and other publications. The constructive comments of Dr Jane Roberts and Dr Paul Bailey are also gratefully acknowledged. Rod Smith of Australia provided information regarding the waterbirds of Thomsons Lake. Alan Rossow of Murdoch University prepared Figures 1 and 2.

ENVIRONMENTAL WATER REQUIREMENTS FOR WETLANDS XI

CONTENTS

TABLE OF CONTENTS

EXECUTIVE SUMMARY ______iii Acknowledgements ...... xi

Table of Contents ______xiii List of Figures ...... xv List of Tables...... xvi

Introduction ______1

1. IDENTIFICATION OF THREATS TO WATER REGIMES ______5

2. REVIEW OF THE LITERATURE DESCRIBING ENVIRONMENTAL WATER ALLOCATIONS ______21 Introduction ...... 21 Environmental Flow Allocations for Rivers...... 22 Environmental Water Allocations for Wetlands...... 23 Case Studies ...... 28 Riverine wetlands ...... 28 (NSW)...... 30 Gwydir Wetlands (NSW) ...... 34 Kerang Lakes (Victoria)...... 35 Wetlands of the Lachlan River Valley (NSW)...... 36 Lake Merreti and Lake Woolpolool (Chowilla Floodplain, ) ...... 39 Barmah-Millewa Forest (Victoria/NSW)...... 40 Groundwater-fed wetlands ...... 43 Lakes of the Gnangara Mound (Swan Coastal Plain, Western Australia) ...... 44 Twin Swamps (WA)...... 48 Great Artesian Basin Mound Springs (SA, NSW, Qld) ...... 49 Conclusion...... 49

ENVIRONMENTAL WATER REQUIREMENTS FOR WETLANDS XIII

3. COMPARISON OF METHODS FOR THE DETERMINATION ENVIRONMENTAL WATER ALLOCATIONS FOR WETLANDS ______51 Introduction ...... 51 Hydrology-driven approaches...... 54 General ...... 54 Examples of hydrology-driven approaches...... 56 Ecology-driven approaches...... 57 General ...... 57 Examples of ecology-driven approaches...... 60 Habitat Analysis Methodology ...... 70 Modelling...... 72 Summary of methods ...... 73 Critical evaluation of methodologies...... 81 Discussion ...... 83

4. FRAMEWORK FOR ENVIRONMENTAL WATER ALLOCATIONS FOR WETLANDS ______85 Framework...... 85 PILOT STUDIES...... 99 Thomsons Lake...... 79 Bool ...... 128 Lower Gwydir Wetlands ...... 140 Boggomoss Springs ...... 147

5. OPPORTUNITIES AND LIMITATIONS______153

REFERENCES ______167

Web Sites ______181

Personal Contacts ______181

XIV ENVIRONMENTAL WATER REQUIREMENTS FOR WETLANDS

CONTENTS

List of Figures FIGURE 1. DISTRIBUTION OF RAMSAR-LISTED WETLANDS WITH THREATENED OR POTENTIALLY THREATENED WATER REGIMES...... 7 FIGURE 2. FRAMEWORK FOR THE DETERMINATION OF ENVIRONMENTAL WATER ALLOCATIONS ...... 5 FIGURE 3. HISTORY OF THE DETERMINATION OF ENVIRONMENTAL WATER ALLOCATION FOR THE MACQUARIE MARSHES...... 33 FIGURE 4. HISTORY OF THE DETERMINATION OF ENVIRONMENTAL WATER ALLOCATIONS FOR WETLANDS OF THE GNANGARA MOUND...... 46 FIGURE 5 HYDROLOGY-DRIVEN RESOURCE-MANAGEMENT APPROACH ...... 57 FIGURE 6. METHODOLOGY FOR ESTIMATING FLOODPLAIN WETLAND WATER ALLOCATIONS BASED ON THE PLANT WATER REQUIREMENTS...... 61 FIGURE 7. DETERMINATION OF ENVIRONMENTAL WATER REQUIREMENTS OF GWYDIR WETLANDS...... 63 FIGURE 8. FRAMEWORK OF THE METHODOLOGY USED IN THE DETERMINATION OF THE ENVIRONMENTAL WATER REQUIREMENTS OF THE WETLANDS OF THE GNANGARA MOUND, ON THE SWAN COASTAL PLAIN, WA...... 66 FIGURE 9. DETERMINATION OF ENVIRONMENTAL WATER REQUIREMENTS FOR TWIN SWAMPS, WA ...... 67 FIGURE 10. ADAPTATION OF HABITAT ANALYSIS METHODOLOGY...... 72 FIGURE 11. FRAMEWORK FOR THE DETERMINATION OF ENVIRONMENTAL WATER ALLOCATIONS...... 87 FIGURE 12. HYDROGRAPH WITH RAINFALL DATA FOR THOMSONS LAKE, WA...... 82 FIGURE 13 RATES OF WATER LEVEL CHANGE AT THOMSONS LAKE...... 83 FIGURE 14. BATHYMETRY, VEGETATION AND WATER LEVEL RECORDS OF THOMSONS LAKE ...... 106 FIGURE 15. CONCEPTUAL MODELLING: SCENARIOS DESCRIBING WETLAND RESPONSE TO CHANGING WATER REGIME (THOMSONS LAKE)...... 119 FIGURE 16. BOOL LAGOON ...... 128

ENVIRONMENTAL WATER REQUIREMENTS FOR WETLANDS XV

List of Tables TABLE 1. LIST OF AUSTRALIAN WETLANDS OF NATIONAL AND INTERNATIONAL IMPORTANCE WITH THREATENED WATER REGIMES...... 9 TABLE 2. SUMMARY AND ASSESSMENT OF METHODS FOR DETERMINING ENVIRONMENTAL WATER ALLOCATIONS FOR WETLANDS...... 75 TABLE 3. CRITICAL EVALUATION OF METHODS...... 82 TABLE 4. PROCESSES WHICH MAY ALTER ASPECTS OF THE WATER BUDGET OF THOMSONS LAKE...... 111 TABLE 5. GENERAL WATER REGIME REQUIREMENTS OF VEGETATION ...... 113 TABLE 6. WATER DEPTH REQUIREMENTS OF EMERGENT MACROPHYTES...... 113 TABLE 7. WATER REGIME REQUIREMENTS OF WETLAND VERTEBRATE FAUNA...... 115 TABLE 8. NUISANCE/PEST SPECIES THAT MAY BE FAVOURED BY CHANGES TO THE WATER REGIME ...... 117 TABLE 9. RELATIONSHIP BETWEEN CRITERIA WATER LEVELS IN M AHD AND WATER DEPTHS ...... 122 TABLE 10. WATER REGIME CRITERIA IN RELATIONSHIP TO DEPTH AND WATER REGIME REQUIREMENTS OF WETLAND VEGETATION AND FAUNA...... 126 TABLE 11. DOMINANT FLORA OF VARIOUS ZONES OF BOOL LAGOON ...... 129 TABLE 12. WATER REGIME REQUIREMENTS OF WETLAND PLANTS OF BOOL LAGOON, AND EFFECTS OF THE ALTERED WATER REGIME...... 133 TABLE 13. WATER REGIME REQUIREMENTS OF WATERBIRDS ...... 134 TABLE 14. WATERBIRD USE OF ...... 135 TABLE 15. VEGETATION COMMUNITIES AT THE GINGHAM WATERCOURSE MOST THREATENED BY ALTERED WATER REGIME ...... 140 TABLE 16. NATURE OF ALTERATION TO WATER REGIME AND EFFECT ON VEGETATION AT THE GINGHAM WATERCOURSE ...... 142 TABLE 17. ESTIMATES OF FLOOD FREQUENCIES REQUIRED BY DOMINANT PLANT SPECIES ...... 143 TABLE 18. LIMITATIONS AND OPPORTUNITIES FOR IMPLEMENTING ENVIRONMENTAL WATER ALLOCATIONS FOR WETLANDS...... 159

XVI ENVIRONMENTAL WATER REQUIREMENTS FOR WETLANDS

INTRODUCTION

INTRODUCTION

This project is a component of the National River Health Program, which aims to protect Australia’s water resources. It is an adjunct to the research program undertaken by States and Territories and funded by Environment Australia under the Environmental Flows Initiative. This program lies within the policy context of the Council of Australian Governments Water Reform Framework. Important principles directing the Environmental Flows Initiative include:

environmental flow decisions should be based on sound scientific knowledge

water resource developments should be ecologically sustainable

allocations should be reviewed five years after they are allocated

allocations should be made to allow adjustment of allocations as necessary

methods for determining environmental flows (for given broad geographic areas or types of environment) should be as consistent as possible throughout the country.

This project, Environmental Water Requirements to Maintain Wetlands of National and International Importance, was concerned with the determination of water requirements for important wetlands with water regimes that are threatened by human impacts. The objectives of this project were:

to identify those wetlands in Australia of international and national importance that are threatened by current or future changes to flow regime

to develop a method for determination of appropriate environmental flows that will protect these wetlands against decline in their ecological character

ENVIRONMENTAL WATER REQUIREMENTS FOR WETLANDS 1

to identify the practical limitations and opportunities available for implementation of environmental flows to these systems.

For the purposes of this project, wetlands are defined as lentic waters lacking direct surface connection with the sea. Lakes (including seasonal, ephemeral and permanent), marshes, , forested and shrub swamps, inland deltas, peatlands, , springs, rock pools, and subterranean karst wetlands are covered. Wetland aggregations which include wetlands belonging to these categories have been covered by this project. Wetlands listed as Ramsar sites have been identified as being of international importance and have met one or more criteria including representativeness, uniqueness, or significant flora or fauna. In addition, there are specific criteria associated with waterfowl (ANCA, 1996). The Directory of Important Wetlands (ANCA, 1996) lists wetlands of national and international significance. A wetland may be deemed nationally significant on the basis of

being a good regional example of a wetland type,

its ecological or hydrological role, its role as habitat for fauna at vulnerable life stages,

its provision of for fauna,

supporting 1% or more of the national population of an or plant taxon,

supporting nationally vulnerable or endangered taxa or communities, or

its cultural or historic significance (ANCA, 1996).

This report is presented in five chapters. The first identifies Australian wetlands of international and national significance threatened by changes to water regime and presents a summary of threats on a regional basis (Chapter 1). This is followed by a review of the literature on environmental water allocations for wetlands (Chapter 2). The history of water allocations to the

2 ENVIRONMENTAL WATER REQUIREMENTS FOR WETLANDS

INTRODUCTION

Macquarie Marshes (NSW), the Gwydir wetlands (NSW), Kerang Lakes (Victoria), wetlands of the Lachlan River Valley, Lakes Merreti and Woolpolool of the Chowilla floodplains (SA), the Barmah-Millewa (Victoria/NSW), wetlands of the Gnangara Mound (WA) and Twin Swamps (WA) were examined. In addition, the effects of measures to conserve the water resource of the Great Artesian Basin on mound spring wetlands of this region were examined. This review is followed by a comparison and analysis of various methodologies used for the determination of environmental water allocations for wetlands (Chapter 3). From this a framework was developed (Chapter 4). Finally, opportunities and limitations for environmental water allocations for wetlands were identified (Chapter 5).

ENVIRONMENTAL WATER REQUIREMENTS FOR WETLANDS 3

1. WATER REGIME THREATS

1. IDENTIFICATION OF THREATS TO WETLAND WATER REGIMES

Using the Directory of Important Wetlands and internet and library searches, a total of 231 Australian wetlands of national and international importance were identified as having threatened or potentially threatened water regimes. These are listed in Table 1 together with a description of the nature of the threat, and the State and region in which they are located. Of these wetlands, 38 are Ramsar listed; the locations of these are given in Figure 1. The locations of the other wetlands can be found at the Directory of Important Wetlands website (www.ea.gov.au/wetlands).

In the process of identifying important wetlands threatened by potential or existing water regime threats, it was noted that there are regional issues affecting water regimes of Australian wetlands, in addition to local issues. These regional issues include river regulation, diversion and abstraction in the Murray-Darling Basin, excessive inundation in the Western Australian wheatbelt and parts of the coastal plain, and aquifer draw-down in the Great Artesian Basin (Figure 2). Specific local impacts also affect wetland water regimes. These include hydrological alterations associated with urban and agricultural development.

Australia-wide. the draining of wetlands and damplands to convert wet areas to dry land for urban and agricultural use remains an issue. This is occurring in ’s Wet Tropics and eastern due to agricultural pressure. Urban pressures are perhaps most pronounced on the perimeters of cities and towns undergoing rapid expansion.

ENVIRONMENTAL WATER REQUIREMENTS FOR WETLANDS 5

6 ENVIRONMENTAL WATER REQUIREMENTS FOR WETLANDS

1. WATER REGIME THREATS

Figure 1. Distribution of Ramsar-listed wetlands with threatened or potentially threatened water regimes.

ENVIRONMENTAL WATER REQUIREMENTS FOR WETLANDS 7

Excessive inundation due to rising water table (clearing-related)

Potential elevation of water table (clearing-related)

Abstraction

Aquifer drawdown threatens Great Artesian Basin mound springs

Future mining activity could alter hydrology

Ponded pasture

Diversion for irrigation Potential irrigation for cotton and threats associated with oil and gas exploration Flood mitigation Drainage

Altered hydrology Multiple alterations including due to peat regulation, drainage, diversion, moss extraction abstraction (irrigation-related) and drainage and rising water tables

Figure 2 Current and potential threats to wetland water regimes mapped according to IBRA regions.

8 ENVIRONMENTAL WATER REQUIREMENTS FOR WETLANDS

2. LITERATURE REVIEW

Table 1. List of Australian wetlands of national and international importance with threatened water regimes. Except where indicated, the information is from the Directory of Important Wetlands.

Wetland Nature of flow regime threat State Region Adelaide River Floodplain System Saltwater intrusion and groundwater extraction NT Top End Coastal Alexandra Bay Hydrology may be altered by tourist and recreational development QLD Wet Tropics Alexandra Palm Forest Lowering of watertable caused by drains installed for agricultural purposes QLD Wet Tropics Apsley Marshes Drains have been dug TAS Freycinet Aramac Springs Aquifer drawdown caused by water harvesting from Great Artesian Basin. Excavation QLD of springs to increase water storage (Jackson, 1992) Floodplain Damming, water harvesting from channels & billabongs. QLD Darling Riverine Threat of excessive water use associated with cotton production Bambaroo Coastal Aggregation Hydrology altered by drainage for agriculture QLD Wet Tropics Banongill Network Regulation of flow VIC Victorian Volcanic Plain Banrock Wetland Complex Water abstraction SA Murray-Darling Depression Barmah-Millewa Forest Regulation of the Murray and Edward Rivers alters hydrology VIC/NSW Potential threat from groundwater extraction WA Swan Coastal Plain Big Badja Swamp Drainage of wetland NSW South East Highlands Billabong Reserve Potential threat from abstraction of water for domestic purposes by a nearby roadhouse VIC South East Coastal Plain Black Swamp Irrigation NSW Riverina Black Swamp Altered hydrology due to drainage and road construction VIC Riverina Blackmans Lagoon Potential threat from drainage TAS Ben Lomond Blencoe Falls- Blencoe Creek Proposed dam above falls for a hydroelectric scheme QLD Blue Lake Sedimentation has occurred, producing deltas NSW Blue Mountains Sedge Swamps Water diversion NSW Boggomoss Springs Aquifer drawdown caused by water harvesting from Great Artesian Basin. Potentially QLD South some springs could be flooded by proposed Nathan River Dam. Bool & Hacks Lagoons Changed water levels in Bool Lagoon threatens recruitment of Melaleucas (LWRRDC, SA Naracoorte Coastal Plain 1997b). Rising water tables are a potential threat Booligal Wetlands Lachlan River regulation NSW Riverina

ENVIRONMENTAL WATER REQUIREMENTS FOR WETLANDS 9

Booragoon Lake Potential: excessive inundation WA Swan Coastal Plain

Wetland Nature of flow regime threat State Region Bowling Green Bay Hydrology of Barratta Creek & the which drain into these wetlands have QLD Brigalow Belt North been modified- diversion to this system for irrigation Brixton Street Swamps Groundwater extraction WA Swan Coastal Plain Broke Inlet System Possible future water supply demands WA Warren Bromfield Swamp Attempts to alter drainage patterns and to mine peat QLD Wet Tropics Bulloo Overflow /Carypundy Swamp Potential alteration to hydrology: upstream removal of water would reduce flood frequency NSW

Bunguluke Wetlands, Tyrrell Creek & Diversion (both to the wetlands and away from them) and levee banks for flood mitigation VIC Murray-Darling Depression Lalbert Creek Burdekin Delta Aggregation Diversion for irrigation:an artificial aquifer recharge pumping program- divertes water from QLD Brigalow Belt North the -irrigated agriculture Burdekin-Townsville Coastal Diversion for irrigation from Burdekin River into these wetlands QLD Brigalow Belt North Aggregation Byenup Lagoon System Potential: peat mining & catchment drainage WA Caledonia Drainage lines may be formed by cattle trampling VIC Australian Alps Camballin Floodplain Diversion (dam) WA Cape Leeuwin System Current: abstraction from spring feeding swamp. Potential: further reduction of spring flow WA Warren

Cape Melville- Bathurst Bay Hydrology could be disturbed by future coal mining QLD Cape Range Subterranean Waterways Abstraction for town water supply, 1998 petroleum exploration WA Carnarvon Carbrook Wetland Aggregation Alteration of the hydrological regime, clearing. Potential drainage of swamp for housing QLD South Eastern Queensland estates Cemetery Swamp Lake of water supply VIC Riverina Central Highlands Peatlands Altered hydrology: may have been caused by harvesting of Sphagnum, road construction, VIC South East Highlands logging Chandala Swamp Diversion WA Swan Coastal Plain Clarence River Filling &draining of wetlands NSW NSW North Coast Cobden-Terang Volcanic Craters Drainage & water extraction VIC Victorian Volcanic Plain Coomoderry Swamp Altered hydrology NSW Sydney Basin

10 ENVIRONMENTAL WATER REQUIREMENTS FOR WETLANDS

2. LITERATURE REVIEW

Cooper Creek Overflow Swamps- Proposed irrigated cotton production QLD Channel Country Windorah

ENVIRONMENTAL WATER REQUIREMENTS FOR WETLANDS 11

Wetland Nature of flow regime threat State Region Swamps- Nappa Merrie Upstream- cotton development QLD Channel Country Cooper Creek- Wilson River Junction Drilling/pumping sites associated with oil/gas exploration and exploitation QLD Channel Country Corella Lake Prolonged inundation ( deaths) NT Mitchell Grass Downs Corio Bay Wetlands Altered hydrology in one area caused by a barrage QLD Cowley Area Wetlands in the area have been cleared & drained for agriculture: potential for intensification QLD Wet Tropics and continuation of the clearing & draining Coyrecup Lake Excessive inundation WA Creswick Swamp Hydrology probably severely altered VIC Victorian Midlands Cuba Dam Impoundment NSW Riverina Cundare Pool/ Regulation via a diversion channel & regulator at inlet & outlet VIC Victorian Volcanic Plain Dalhousie Springs Water extraction, drawdown SA Daly-Reynolds Floodplain-Estuary Saltwater intrusion. Potentially changed flooding regimes due to clearing for NT Top End Coastal System horticulture/mixed farming D'Arcy's Lagoon Drainage TAS D'Entrecasteaux Darling Anabranch Lakes Water regulation NSW Murray Darling Depression Davies Plain Drainage lines may be formed by cattle trampling, 4 wheel driving, hiking. VIC Australian Alps Dismal Swamp- Water Park Creek Sandmining could alter hydrology. Increased groundwater flow. QLD Central Mackay Coast Doggerup Creek System Vegetation clearance causing alterations to inflow WA Warren Doongmabulla Springs Aquifer drawdown caused by water harvesting from Great Artesian Basin QLD Desert Uplands Dragon Tree Soak Camel damage could result in exposure & drying out WA Dublin Peat harvesting TAS Central Highlands Edithvale- Seaford Wetlands Alteration of hydrology including flood mitigation VIC South East Coastal Plain Edmund Kennedy Wetlands Potential effects on hydrology by the agriculture of the area QLD Wet Tropics Elizabeth Springs Aquifer draw down caused by water harvesting from the Great Artesian Basin QLD Mitchell Grass Downs Swamps System Clay extraction and changed landuse may lower water levels WA Swan Coastal Plain Eubanangee- Alice River Floodplain surrounding Eubanagee has been cleared & drained for sugarcane production; QLD Wet Tropics potential for exaceration of the above Finniss Floodplain and Fog Bay System Saltwater intrusion NT Top End Coastal

12 ENVIRONMENTAL WATER REQUIREMENTS FOR WETLANDS

2. LITERATURE REVIEW

First (The Marsh) Excessively high water levels VIC Riverina

ENVIRONMENTAL WATER REQUIREMENTS FOR WETLANDS 13

Wetland Nature of flow regime threat State Region Fitzroy Present: altered hydrology to prevent tidal intrusion. Potential: altered hydrology from QLD Brigalow Belt South proposed dams Floodplain Damming and water harvesting QLD Brigalow Belt South Folly Lagoon Drainage for agriculture TAS Tasmanian Midlands Groundwater extraction (public & private) WA Swan Coastal Plain Fortescue Marshes Dam WA

Fosters Swamp Lack of water supply, used for sewage effluent disposal VIC Riverina Fraser Island Mining QLD South Eastern Queensland Gibbs Road Swamp System Groundwater extraction (public & private) WA Swan Coastal Plain Gnamma Holes Camels occasionally drink gnamma holes dry WA Gibson Desert Gingilup- Jasper Wetland System Groundwater extraction WA Warren Ginini and Cheyenne Flats Localised change in drainage caused by past peat moss extraction ACT Australian Alps Great Cumbung Swamp Regulation- Lachlan River. A reduction of mid-level floods (with return period 3-20 years), NSW Riverina and an increase in low flows (< 3 years) return periods with little impacts on major floods. Levees within the swamp (DLWC, 1998) Gunbower Island River regulation causing altered flooding regime, illegal deposition of irrigation drainage VIC Riverina Guraga Lake Water diversion WA Swan Coastal Plain Gurra Lakes Wetland Complex Altered water regime indicated by death of Gums SA Murray-Darling Depression Gwydir Wetlands: Gingham and Lower Irrigation pressures on , irrigation operations NSW Darling Riverine Plains Gwydir wetlands Harmer River- Shelburne Bay Hydrology could be disturbed by future mining of silica sands QLD Cape York Peninsula Aggregation Hattah Lakes Altered flows in the VIC Murray-Darling Depression Floodplain Draining & filling of wetlands for agriculture QLD Wet Tropics Heywoods Lake Diversion VIC Murray-Darling Depression Hird's Swamp Irrigation tailwater disposals VIC Riverina Horse Park Wetland Possible changes to hydrology from proposed urbanisation ACT Innisfail Area Hydrology in northern section has been altered by drains QLD Wet Tropics Irwin Flat Increased flow (potential) SA Murray-Darling Depression

14 ENVIRONMENTAL WATER REQUIREMENTS FOR WETLANDS

2. LITERATURE REVIEW

Wetland Nature of flow regime threat State Region Johnson's Swamp Irrigation tailwater disposals VIC Riverina Joondalup Lake Groundwater extraction WA Swan Coastal Plain Kanyapella Basin Artificial hydrological regime VIC Riverina Karakin Lakes Possible future groundwater extraction WA Swan Coastal Plain Kemps Marsh Drainage (potential) TAS Central Highlands Koondrook and Perricoota Forests Regulation- Murray River NSW Riverina Kooraweera Lakes Hydrology altered by channel construction & alteration of natural channels VIC Victorian Volcanic Plain Kosciusko Alpine , Bogs and Lakes Drainage could be altered by trampling in some fens/bogs NSW Australian Alps

Kow Swamp Abstraction for irrigation VIC Riverina Lachlan Swamp (part of mid Lachlan Regulation- Lachlan River NSW Riverina Wetlands) Surface flow regime modification, rising water-table VIC Murray-Darling Depression Lake Bael Bael Altered hydrological regime: floods too frequently & holds water for too long VIC Riverina Lake Barlee Potential for mining of lake bed WA Murchison Lake Bookaar Dams, potential for further dams VIC Victorian Volcanic Plain Lake Brewster Used for water storage- reduced variability of water levels. Is dried out before summer to NSW Riverina reduce losses due to evaporation. Lake Broadwater Irrigation QLD Brigalow Belt South Lake Colongulac The lake receives discharge from the Sewerage Treatment Plant VIC Victorian Volcanic Plain Input dammed/ diverted VIC Victorian Volcanic Plain Lake Cowal/Wilbertroy Wetlands Proposed gold mine (tailings dam, drainage proposals, levee bank construction) NSW NSW South Western Slopes Lake Cronin Disturbances to the catchment area may alter hydrology: elevation of hypersaline WA Mallee groundwater table would be catastrophic Development may have led to reduced water inflow to the lake. TAS Tasmanian Midlands Lake Elphinstone Water pumped from the lake: is now dry QLD Brigalow Belt North Lake Eyre Mound Springs Water drawdown: increased extraction of groundwater from artesian bores SA Stony Plains Lake George Lake is dammed on one side NSW South East Highlands Lake Gnarput Altered hydrology as outlet to Lake Corangamite has been lowered VIC Victorian Volcanic Plain System Excessive inundation WA

ENVIRONMENTAL WATER REQUIREMENTS FOR WETLANDS 15

Wetland Nature of flow regime threat State Region River regulation: diminished flow VIC Murray-Darling Depression Lake Kelly & Stevensons Swamp Stevensons Swamp used to dispose of local drainage VIC Riverina Lake Lalbert Diversion. Proposed redistribution of flood flow would ensure flooding every 2 VIC Murray-Darling Depression years. Lake McLarty System Groundwater extraction on small rural holdings WA Swan Coastal Plain Lake Mipia Area Road crossing- interrupts flow of water but has not caused any major changes to vegetation QLD Channel Country

Lake Newland Water withdrawals SA Eyre and Yorke Blocks Lake Nichebulka Diversion would be a threat NSW Lake Ranfurly Disposal of saline groundwater VIC Murray-Darling Depression Lake Thetis Change to hydrology WA Swan Coastal Plain Salt extraction from one side of the lake may affect the groundwater VIC Murray-Darling Depression Lake Walbyring Excessive inundation WA Avon Wheatbelt Lake Wellington Wetlands Altered hydrological regime due to dams, drains and levee banks have altered river flow & VIC South East Coastal Plain flow between wetlands Lake William Used as an evaporation basin VIC Riverina Lake Woods Prolonged inundation (tree deaths) NT Mitchell Grass Downs Lashmar Lagoon Flooding: surrounding land is cleared SA Lofty Block Lindsay-Werrikoo Wetlands Drainage & water regulation VIC Narracoorte Coastal Plain Little Lake Charm, Kangaroo Lake & Abstraction for irrigation. The hydrology of Kangaroo Lake is highly modified: level does VIC Riverina Racecourse Lake not fluctuate naturally (also Racecourse Lake) Remobilised could alter drainage. Threat of drainage for agriculture TAS Ben Lomond Loch Luna Wetland Complex Water abstraction SA Murray-Darling Depression Loch McNess System Groundwater extraction WA Swan Coastal Plain Drainage TAS Furneax Long Swamp Past & proposed future peat extraction- lower water table NSW Sydney Basin Longneck Lagoon Weir impedes drainage NSW Sydney Basin Loveday Swamps Excessive inundation: drowned Red River Gums SA Murray-Darling Depression Lowbidgee Floodplain Water regulation, channelling & diversion NSW Murray Darling Depression

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Wetland Nature of flow regime threat State Region Lower Wetlands Artificial breaching of Aire River mouth bar has resulted in lowering of lake water levels VIC South East Highlands

Lower Floodplain Elevated water table due to irrigation VIC Riverina Lower Lough Calvert & Lake Drainage diversion- reduced frequency & extent of inundation VIC Victorian Volcanic Plain Thurrumbong Lower Mirrool Creek Floodplain Irrigation NSW Riverina Lower Murray Swamps Levee banks- floodplain; stressed Red River Gums SA Murray-Darling Depression Lower Wetlands System Various engineering works now alter the hydrology preventing sheetflow over the Vic South East Corner floodplain, as previously occurred (DCE, 1992) Macquarie Marshes River regulation, abstraction for irrigation NSW Darling Riverine Plains Mandora Potential: groundwater extraction for cotton WA Great Sandy Desert Maringup Lake Groundwater extraction (further) WA Warren Mary Floodplain System Saltwater intrusion NT Top End Coastal McCarley's Swamp (Ludlow Swamp) Excessive inundation:seepage of water from adjacent perched artificial lakes that receive WA Swan Coastal Plain mine effluent)

McLeods Morass Stormwater, sewage effluent VIC South East Coastal Plain Menindee Lakes Regulation: dam & weir on the NSW Darling Riverine Plains Merrowie Creek River regulation & abstraction for irrigation NSW Riverina Mid Murrumbidgee Wetlands River regulation NSW Riverina Middle Lough Calvert Artificial hydrological system VIC Victorian Volcanic Plain Millstream Pools Groundwater extraction WA Pilbara Mitchell River Fan Aggregation Some development of ponded pasture QLD Moates Lake System Potential: hydrology could be altered by further catchment clearing WA Jarrah Forest Mortijinup Lake System Excessive inundation WA Esperance Plains Mount Buffalo Peatlands Drainage lines could be formed by walkers VIC Australian Alps Moyle Floodplain and Hyland Bay Potential saltwater intrusion NT Top End Coastal System Mt Soho Swamps Inappropriate fire management could result in exposure, & consequent loss of water, also WA Warren change in discharge to swamp. Murrays Lagoon Flooding SA Lofty Block

ENVIRONMENTAL WATER REQUIREMENTS FOR WETLANDS 17

Wetland Nature of flow regime threat State Region

Naen Naen Swamp & Gum Lagoon Lack of surface flows: diversion of Marcollat Watercourse SA Naracoorte Coastal Plain Narran Lakes Upstream extraction for irrigation; QLD portion of the NSW Darling Riverine Plains Natimuk Lake, Natimuk Creek & Lake Water level manipulation. Raising the outlet at Natimuk Lake has restricted flows along VIC Murray-Darling Depression Wyn Wyn Natimuk Creek to Lake Wyn Wyn New England Wetlands Drainage, damming NSW New England Tableland Newington Wetlands Seawalls reduce areas of & saltmarsh NSW Sydney Basin Wetlands Urban expansion; clearing & filling of saltmarshes QLD South Eastern Queensland O'Hares Creek Catchment Sand & clay extraction NSW Sydney Basin Orford Bay- Sharp Point Dunefield Future- mining QLD Cape York Peninsula Paroo Overflow Threatened by abstraction (Timms, 1997). Lower flow to wetlands & lower variability NSW Mulga Lands Parry Floodplain Current: Regulation; Lakes Kununurra and Argyle. Receives declining frequency of floods; WA may result in decreased waterbird habitat (Schofield, 1998). Potential: rising water table (Schofield, 1998). Airport Woodland Swamps Drainage of swamp areas has occurred WA Swan Coastal Plain Pike-Mundic Wetland Complex Possible. Groundwater seepage associated with irrigation- caused salinity changes SA Murray-Darling Depression Groundwater extraction WA Esperance Plains Port Musgrave Aggregation Future- (possible) bauxite mining QLD Cape York Peninsula Port of Cairns and Trinity Inlet Wetlands drained, filled QLD Wet Tropics Princetown Wetlands Regulation of upstream water flows, drainage of wetlands north-east of Princetown VIC South East Highlands Raak Plain Groundwater hydrology affected by mining for gypsum VIC Murray-Darling Depression Wetland Complex Changes in flows and regimes due to water regulation SA Murray-Darling Depression Rock Flats Drainage can be altered by walkers ACT Australian Alps Lakes Groundwater extraction WA Swan Coastal Plain Round Mountain Diversion NSW New England Tableland Rowles Lagoon System Excessive inundation WA Coolgardie Russell River Drainage associated with canefields QLD Wet Tropics Second Marsh (Middle Marsh) Altered hydrology: increased flooding frequency; water is held for longer, affected by VIC Riverina groundwater intrusion Southeast Karumba Fan Aggregation Future development of ponded pasture QLD Gulf Plains Spectacle Lakes Water abstraction SA Murray-Darling Depression

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2. LITERATURE REVIEW

Wetland Nature of flow regime threat State Region Spectacles Swamp Groundwater extraction WA Swan Coastal Plain Spring Tower Complex Dewatering of limestone aquifer QLD Einasleigh Uplands Swanpool/Belmore Swamp Drainage NSW NSW North Coast Tang Tang Swamp Rising water table VIC Riverina The Coorong, Lake Alexandina & Lake Regulation, drainage SA Naracoorte Coastal Plain Albert Third Marsh (Top Marsh) Altered hydrology: increased flooding frequency; water is held for longer VIC Riverina Third, Middle and Reedy Lakes Altered hydrology: lakes were previously marshes VIC Riverina Thomsons Lake Groundwater extraction WA Swan Coastal Plain Tookayerta & Finniss Catchments Draining SA Lofty Block Excessive inundation WA Avon Wheatbelt Tower Hill Lowering water levels due to groundwater changes with irrigation VIC Victorian Volcanic Plain Town Swamp Irrigation tailwater disposal VIC Riverina - Murray River Floodplains Hydrology of deep water lagoons affected by extensive agricultural drainage networks. QLD Wet Tropics Potential: establishment of new drainage networks Unnamed Wetland BEN015TA Possibly future drainage & infilling TAS Ben Lomond Unnamed Wetland FUR011TA Altered drainage TAS Furneax Unnamed Wetland FUR013TA Altered drainage TAS Furneax Unnamed Wetland WSW009TA Drainage TAS West and South West Upper Lough Calvert Diversion of floodwater & run-off due to road embankments & the Lough Calvert Drainage VIC Victorian Volcanic Plain Scheme Upper Naas Creek Changes to drainage caused by cattle & sheep trampling, also by channels dug for sheep ACT Australian Alps watering holes Vasse-Wonnerup Wetland System Landfill of floodplain wetlands WA Swan Coastal Plain Wallenjoe Wetlands Elevated water levels due to drainage discharge VIC Riverina Wannamal Lake System Current: excessive inundation. Potential: water diversion, vegetation clearance WA Swan Coastal Plain Watervalley Wetlands Rising groundwater, changed water flows SA Naracoorte Coastal Plain Werai Forest River regulation NSW Riverina Willie Creek Wetlands 1989-1990 creation of a barrage to raise lake water levels, creation of a dam 1.5 km east of WA Dampierland swamp- reduced surface run-off. Potential: groundwater extraction for Broome expansion

ENVIRONMENTAL WATER REQUIREMENTS FOR WETLANDS 19

Wetland Nature of flow regime threat State Region Wingecarribee Swamp Peat mining has led to the collapse and drainage of the wetland (Tranter, 1999) NSW Sydney Basin Wooleen Lake Potential for siltation of the lake if overgrazing occurred WA Murchison Wyvuri Swamp Hydrology affected by road & drain construction QLD Wet Tropics Yalgorup Lakes System Extraction of groundwater (& interference with seepage near new rural smallholdings) WA Swan Coastal Plain Yambuk Wetlands Water level manipulation; drainage & channeling has altered the hydrology VIC South East Coastal Plain Yantabulla Swamp (Cuttaburra Basin) Possible future upstream abstraction NSW Mulga Lands Yaouk Swamp Peat mining. Also much of the swamp has been drained NSW South East Highlands Yealering Lakes System Excessive inundation WA Avon Wheatbelt Yellilup Yate Swamp System Excessive inundation WA Esperance Plains Yorkrakine Rock Pools Water diversion WA Avon Wheatbelt

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2. LITERATURE REVIEW

2. REVIEW OF THE LITERATURE DESCRIBING ENVIRONMENTAL WATER ALLOCATIONS FOR WETLANDS

Introduction

This review examined the determination of environmental water allocations for wetlands in Australia. The wetlands considered were standing enclosed water bodies, and include permanent, seasonal and ephemeral waters. The provision and maintenance of appropriate water regimes is considered the most important management issue for many Australian wetlands (Adam, 1997). Water regimes of many wetlands have been altered by regulation, extraction of water for agricultural, domestic and industrial uses, the use of wetlands as areas for water storage, and changes in land use. Human impacts on wetland water regimes can result in both increased and decreased inundation, as well as altered variability in inundation and seasonality (ANCA, 1996). Davis and Froend (1999) noted that water levels in urban wetlands on the Swan Coastal Plain in Western Australia have risen due to land clearing resulting in local rises in the water table and increased surface run-off. Groundwater extraction also poses a threat to some wetlands in the same region in the form of lower water levels and prolonged dry phases. Management of environmental water allocation for wetlands in Australia has mainly focused on wetland systems where the hydrology is altered by water extraction, however the issue of drainage into wetlands and inundation as a result of rising water tables also needs to be addressed. That is, wetlands can have ‘too much water’ as well as ‘too little water’.

ENVIRONMENTAL WATER REQUIREMENTS FOR WETLANDS 21

Environmental Flow Allocations for Rivers

In both Australia and overseas, environmental water allocation has focussed on rivers. Initially the prime motivating concern was improving fish habitat and meeting fish passage requirements. Later, broader issues were considered, such as the maintenance of ecosystem processes (Arthington and Pusey, 1992). Approaches include methods based on historical discharge, habitat analysis and species requirements (Swales and Harris, 1995).

Approaches to the determination of environmental flow allocations in rivers have included two historical discharge or ‘rule-of-thumb’ methods, the Montana Method and Flow Duration Curve Analysis. These are based on the use of historical flow records, using a fixed proportion of the ‘natural’ flow which occurred prior to development. There is generally a strong emphasis on maintaining minimum flows (Pusey, 1998). For this reason, their reliance on criteria developed overseas, they are not considered suitable for Australian streams (Arthington and Pusey, 1992; Richardson, 1986). Australian river systems are characterised by high flow variability. Preservation of periods of low or no flows are important for the maintenance of their ecological character.

Habitat Analysis Methodology (Burgess and Vanderbyl, 1996) was developed in Queensland to determine environmental flows for rivers and streams (Arthington, 1998). It is based on a panel of experts workshop, with four distinct elements:

22 ENVIRONMENTAL WATER REQUIREMENTS FOR WETLANDS

2. LITERATURE REVIEW

identification of generic habitat types existing within the catchment

determination of the flow-related ecological requirements of each habitat

development of bypass flow strategies to meet those requirements

development of a monitoring strategy to check the effectiveness of flow strategies

(Arthington, 1998, p.26).

Instream habitat modelling methods, such as Instream Flow Incremental Methodology (IFIM), are based on the determination of habitat preference curves for species. Habitat availability is modelled for change in discharge (Swales and Harris, 1995).

The Holistic Approach to environmental water allocation assumes that if the essential components of the natural flow regime are incorporated into the modified flow regime, the biota should persist and the ecological integrity of the ecosystem should be maintained (Arthington, 1998). The essential components of the natural flow regime are determined from an analysis of historical flow records (Pusey, 1998). Where the Holistic Approach is used for the determination of environmental flows in rivers the entire ecosystem and geomorphic processes associated with flows are examined. Water quantity is described in terms of the effect of velocity on the maintenance of such habitats as riffles. Habitat Analysis Methodology is considered to fit within the Holistic Approach (Arthington, 1998).

Environmental Water Allocations for Wetlands

ENVIRONMENTAL WATER REQUIREMENTS FOR WETLANDS 23

Environmental water allocation for wetlands associated with river systems has frequently been incorporated into the flow allocation process for the river system [eg, the Murrumbidgee wetlands (Shields, 1998)]. Although developed primarily for rivers, the Holistic Approach to environmental flow determination is also considered applicable to wetlands (Arthington and Pusey, 1992). Essential components of a wetland’s water regime include the quantity of water, and the timing, duration and frequency of inundation (McCosker, 1998). The use of Habitat Analysis Methodology in wetland environmental water allocations could involve the identification of habitat types according to depth or frequency/duration of inundation. Both Habitat Analysis Methodology (Burgess and Vanderbyl, 1996) and Young et al.’s (1999) Environmental Flows Decision Support System (EFDSS) allow for the consideration of wetlands as one habitat or zone, alongside riverine habitats and zones.

Wetland environmental water allocation however differs from that of rivers in that there is not such a direct relationship between water quantity and geomorphic processes in wetlands. Variability of water quantity over time in wetlands results in habitats of different depths. These habitats are characterised by particular plant and waterbird communities. There is generally a close connection between water quantity and the spatial extent of wetland habitat. For example, on the Chowilla floodplain, a relatively small decrease in flood volume can result in a large reduction in the inundated area (Taylor et al., 1996).

There are two main approaches to wetland environmental water allocation, based on hydrology and ecology respectively (Gippel, 1996). Hydrology- driven approaches are similar to the historical discharge methods described above for rivers. They involve the attempted description and reinstatement of the water regimes that existed prior to development. Information regarding the

24 ENVIRONMENTAL WATER REQUIREMENTS FOR WETLANDS

2. LITERATURE REVIEW pre-development water regime is gathered from historic data where these exist. Modelling may be required where historic data are not available. The Holistic Approach of environmental water allocation for rivers is hydrology-driven in that it is based on incorporating the essential elements of the pre-development flow regime into the modified flow regime. The ecology-driven approach involves estimating the water regime requirements of wetland species, communities and ecosystem processes. The determination of environmental water allocations is based on meeting these requirements.

While the determination of environmental flows for rivers generally occurs at large scales, with the examination of entire river systems, environmental water allocations for wetlands may sometimes occur at much smaller spatial scales. Roberts et al. (2000) consider that it may be possible to return small isolated wetlands to their pre-development water regimes through the use of regulators (water gates) or other devices. In contrast, they consider that for large wetland systems downstream of consumptive demand for water, this will not be possible. In these systems they argue that a realistic goal is rehabilitation rather than restoration. They describe a process, with steps, for the determination of the water regime requirements of vegetation. The water regime requirements of vegetation have frequently been examined in the development of water management plans for wetlands (eg McCosker and Duggin, 1993; Keyte, 1994; WAWA, 1995).

Invasive species are frequently favoured by alterations to water regimes. Examples include the invasion of the weed Phyla canescens (lippia) associated with reduced water quantity (Keyte, 1994), and the increased spawning of carp in the Barmah Forest floodplains associated with river regulation (Blanch, 2000). Environmental water allocations may include water management strategies to control invasive species. Similarly, environmental water

ENVIRONMENTAL WATER REQUIREMENTS FOR WETLANDS 25

allocations for wetlands may incorporate measures to protect endangered species or communities.

Riverine wetlands Water regimes of the following riverine wetlands are managed to meet environmental objectives:

Macquarie Marshes (north-west NSW).

Lower Gwydir Basin Wetlands (northern NSW).

Kerang Lakes (Victoria).

Wetlands of the Lachlan River Valley (southern inland NSW).

Lake Merreti and Lake Woolpolool (Chowilla Floodplain, River Murray SA)

Barmah-Millewa Forest (Victoria-NSW border)

Groundwater-fed wetlands Groundwater-fed wetlands which are the subject of environmental water allocations include:

Lakes of the Gnangara Mound on the Swan Coastal Plain in Western Australia

Twin Swamps, also on the Swan Coastal Plain, Western Australia

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2. LITERATURE REVIEW

The determination of environmental water allocations for these wetlands was reviewed by treating each as a case study. Measures aimed at protecting the water resources of the Great Artesian Basin are also briefly reviewed. These measures have the effect of protecting mound springs, although generally they are designed to protect the water resource for consumptive use.

ENVIRONMENTAL WATER REQUIREMENTS FOR WETLANDS 27

CASE STUDIES Riverine wetlands

River regulation occurs in many regions of Australia, however it is particularly widespread in the Murray Darling Basin. It results in the alteration of wetland water regimes. Riverine wetlands may be divided into two broad categories: floodplain wetlands and terminal wetlands. Dams can affect floodplain wetlands by capturing flood pulses which would otherwise have led to overbank flows to floodplains (Kingsford, 2000). This water is later released to the channel for diversion for consumptive uses. The resultant increased low flows have resulted in increased permanency of the water regimes of some floodplain wetlands. The water regimes of floodplain wetlands can also be altered by conversion into off-river storages, or flooded by dams (Kingsford, 2000). Dams and diversions lead to an overall reduction in the quantity of water flowing to terminal wetlands (Brereton, 1994). Other water regime issues for wetlands resulting from river regulation include over-allocation of water for consumptive use, loss of connectivities, altered hydrology caused by levee banks, and loss of variability in water regimes, including reduced flooding and the loss of seasonality. Infrastructure such as regulators and water supply channels may be necessary to manage riverine wetland water regimes to meet environmental objectives (Allan and Lovett, 1997).

In the following case studies, there is an emphasis on the effect of altered water regimes on waterbird breeding. This is because colonial waterbirds rely on flooding to breed, and breed only in a few large floodplain wetlands in Australia (Marchant and Higgins, 1990; Kingsford, 2000). Alterations to water regimes which adversely affect their breeding could therefore impact continental populations (Kingsford and Johnson, 1999, cited in Kingsford, 2000).

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2. LITERATURE REVIEW

ENVIRONMENTAL WATER REQUIREMENTS FOR WETLANDS 29

Macquarie Marshes (NSW) The Macquarie Marshes is a large (200 000 hectare) semi-permanent wetland which is inundated by the (Directory of Important Wetlands website). The Macquarie River generally terminates at the Marshes, except during large floods, when it flows through to the Darling River (Kingsford, 2000). The Marshes are a Ramsar site and are of considerable importance for waterbirds (Directory of Important Wetlands website). Upstream extraction has occurred since European settlement but increased with the construction of the Burrendong Dam in the late 1960s and the Windamere Dam in the early 1980s (Allan and Lovett, 1997). During the design of the Burrendong Dam, it was calculated that a release of 50 000 ML would result in the filling of levee banks at waterbird breeding sites. This release was promised but was not delivered for economic and political reasons; in 1967 only 18 500 ML was granted to the Marshes. In the 1986 Macquarie Marshes Water Management Plan, the allocation was increased to 50 000 ML (known as a Wildlife Allocation), based on the earlier calculation (Brereton, 1994). The main objective was the protection of waterbird habitat (DLWC and NPWS, 1996). This quantity was found however to be inadequate, due to increased irrigation in the area (DLWC and NPWS, 1996). It has been estimated that the Macquarie Marshes has been reduced in area by approximately 40 - 50 % over 50 years, resulting in a major loss of waterbird habitat (Kingsford and Thomas, 1995).

In 1994 the 1986 MMWM Plan was reviewed, a process which resulted in the 1996 Water Management Plan (Allan and Lovett, 1997) (Figure 1). Objectives of this Plan were:

To secure the amount of water needed for the maintenance and restoration of the Marshes, and

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2. LITERATURE REVIEW

To meet the obligations of the and other international nature conservation agreements to which Australia is a signatory.

(DLWC and NPWS, 1996, p.3).

ENVIRONMENTAL WATER REQUIREMENTS FOR WETLANDS 31

The determination of the revised Wildlife Allocation was based on a detailed study involving the examination of

detailed vegetation maps from 1949, 1963 and 1991,

Landsat TM Imagery flood maps from 1987 onwards,

river gauging data since 1895, and

plant water requirements.

The above list of data examined indicates that both hydrology- and ecology- driven approaches were used. The historical water regime was examined, as were plant water requirements and changes in vegetation.

As a result, the Wildlife Allocation was increased to 125 000 ML per year in the 1996 Plan, with its release timed to match rainfall events. Provision was made for discretionary use to enable the completion of major breeding events. Irrigators’ access to off-allocation water was reduced1 as were overall diversions for irrigation (from 395 000 ML per year to 340 000 ML per year). Water bird breeding requirements were considered in the 1996 Plan in terms of flooding extent and duration, and the need to maintain living Red River Gums for nest sites. Successful breeding of colonial nesting water birds is a performance indicator of the 1996 Plan (DLWC and NPWS, 1996). Inclusion of performance indicators in the Plan allow for the assessment of the water management regime. An outline of the history of environmental water allocations to the Macquarie Marshes is given in Figure 3.

1 Off-allocation in regulated river systems refers to the period “when natural system inflows downstream of the storage, or storage overflows, significantly exceed immediate consumptive demands” (DLWC and NPWS, 1996, p.32). Generally water extracted by irrigators during off-allocation is not debited against their volumetric water allocation.

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2. LITERATURE REVIEW

1986 Water Management Plan (WMP) Wildlife Allocation delivered an environmental water allocation of 50 000 ML to the Marshes, based earlier calculation for waterbird requirements

Monitor Deficiencies in 1986 WMP identified (inadequate Wildlife Allocation)

1996 Water Management Plan • Increased Wildlife Allocation • Capped off-allocation to increase flooding • Timing of wildlife allocation to match rainfall events and allow completion of significant waterbird breeding events

Monitor Check against performance indicators

______Future Refine performance indicators (proposed in DLWC and NPWS, 1996)

Figure 3. History of the determination of environmental water allocation for the Macquarie Marshes

ENVIRONMENTAL WATER REQUIREMENTS FOR WETLANDS 33

Gwydir Wetlands (NSW) This wetland aggregation occurs as a result of the Gwydir River in northern NSW giving way to overland flow due to an extremely low gradient (Allan and Lovett, 1997). The River terminates in the Gwydir floodplain wetlands, the Lower Gwydir and Gingham watercourses (Keyte, 1994). Part of the Lower Gwydir watercourse has recently been listed as a Ramsar site (Nickson, 1999). The wetlands have declined in size as a result of the commissioning of the Copeton Dam in 1976, together with the expansion of irrigation. After the construction of the dam, demand for irrigation water exceeded expectations, resulting in a serious on-going problem of over-extraction of water. It has been estimated that the quantity of water reaching the wetlands was reduced to only 70% of that which was historically available (Allan and Lovett, 1997). As a result, terrestrial vegetation and the weed lippia (Phyla canescens) have invaded areas previously dominated by aquatic and semi-aquatic vegetation (Keyte, 1994). Issues to be addressed by environmental water allocations in the Gwydir wetlands are similar to those of the Macquarie Marshes; an overall reduction in water reaching the wetlands as a result of diversion and extraction.

In 1996 an agreement was reached where the wetlands receive the first 500 ML of tributary flows, after which off-allocation is shared evenly between the environment and irrigators. An allocation of 25 000 ML is held in Copeton Dam for the environment. The percentage of this environmental allocation actually delivered to the wetlands is matched to the proportion of the water allocations the irrigators are able to access. For example, if the irrigators can only access 75% of their water allocation, then only 75% of the environmental allocation of 25 000 ML is released to the wetlands (Allan and Lovett, 1997). In the summer of 1998-1999 a large waterbird breeding event occurred, which was seen as indicating the success of the new water sharing rules (Nickson, 1999).

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Kerang Lakes (Victoria)

The Kerang Lakes are situated 300 km north-west of , and cover an area of 110 500 hectares. Water supply for the Lakes is from the River Murray via the Torrumbarry Irrigation System, the System, the Avoca River System and Bendigo Creek. Many of the lakes are Ramsar listed. Those of high conservation significance include Hird and Johnson Swamps, Lake Elizabeth, Lake Wandella, Lake Murphy, Golf Course Lake, Round Lake, Woorinen North Lake, Woorinen South Lake and Lake Cullen. Irrigation and drainage channels divide the lakes, as a result they no longer represent an interconnected system where overflows from one lake affect another. Water regimes in many cases are completely altered due to the use of lakes and streams for the supply of irrigation water (DCNR, 1990; Allan and Lovett, 1997). The lakes are affected by salinity, partly a result of intrusion of saline groundwater. The Victorian government has committed an interim allocation of 27 6000 ML per year to high value wetlands in the north of the state. The Kerang Lakes receive this water, with the primary objective being the reduction of salinity through flushing (Mudgway et al., 1996).

Conservation values of the Kerang Lakes were evaluated in 1989, and recommendations made for the management of their water regimes for the purpose of enhancing conservation values (Lugg et al., 1989). A management plan was drafted in 1990 for Hird and Johnson Swamps (DCNR, 1990). Although these are both Ramsar wetlands, their character has been significantly altered by irrigation development. Prior to the 1920s they were intermittent swamps dominated by black box. Irrigation development resulted in permanent water regimes in the swamps, which led to tree deaths. The management plan identified values and threats. Values included ibis habitat, waterbird breeding, duck hunting and camping. Excessive coverage of Typha spp., Phragmites australis, and Myriophyllum elatinoides were identified as

ENVIRONMENTAL WATER REQUIREMENTS FOR WETLANDS 35

threats to these values, while the preservation of Schoenoplectus validus was seen as beneficial for ibis nesting. Two scenarios were discussed in terms of their likely effects on the coverage of the above wetland plants (especially Typha spp.), as well as the preservation of the ibis rookery, control of carp, and effects on salinity. It was determined that complete drying of each swamp for one year in four, with the swamps not to be dry in the same years, would be the best management option (DCNR, 1990).

The REALM model was used to develop a strategy for the use of the interim allocation in ten of the Kerang Lakes (Hydro Technology, 1995). This model is based on water and salt balances. Wetlands of the Kerang Lakes were categorised as permanent and semi-permanent for the purposes of determining the way in which the allocation would be used. Permanent lakes are to be flushed annually, and semi-permanent water regimes are to be restored to wetlands such as Hird and Johnson Swamps which had become permanently inundated. The managed regime involves a five year flow strategy for ten wetlands, where in any one year some are drained, some filled and some flushed (Hydro Technology, 1995; Mudgway et al., 1996).

Wetlands of the Lachlan River Valley (NSW) Wetlands of the Lachlan Valley cover 400 000 hectares and include the Great Cumbung Swamp, Booligal Swamp, Lake Cowal, Merrowie Creek/ Lake Tarwong and Willandra Creek/ Morrison’s Lake, Lake Brewster and Lake Cargelligo. Lakes Brewster and Cargelligo have been modified for use as water storages (Kingsford, 2000): Lake Cargelligo is maintained at almost full inundation, while Lake Brewster is allowed to dry in summer (Allan and Lovett, 1997). The Great Cumbung Swamp is a terminal wetland of the Lachlan River. Its hydrology is also influenced by the Murrumbidgee River, as it lies on the confluence of these two rivers (Shaikh et al., 1996). This wetland

36 ENVIRONMENTAL WATER REQUIREMENTS FOR WETLANDS

2. LITERATURE REVIEW was historically wet in winter and dry in summer, but since the construction of Wyangala Dam in 1936, some water reaches it in all of the year (Allan and Lovett, 1997). Booligal Swamp has a large ibis rookery, with as many as 40 000 pairs of breeding ibis. Lake Tarwong is considered significant because of its high diversity of birds (Denham and McCauliffe, 1994).

In 1989 and 1990 water was released from Lake Brewster to allow the successful completion of water bird breeding events. In 1992 Environmental Contingency Allocations (ECA) were introduced by the Department of Water Resources in a trial program. An Environmental Flow Package for the Lachlan Valley was developed with the aims of giving the wetlands a more natural flow regime and reducing the impacts of river regulation and water extraction. The initial ECAs were determined using existing knowledge and general ecological principles and were later refined as a result of monitoring (Denham and McAuliffe, 1994). Allocations address water quality problems (such as blue-green algal blooms and salinity) in addition to water quantity issues and are now known as Contingency Allocations (CAs) (Allan and Lovett, 1997).

Contingency Allocations are targeted at waterbird breeding events, in particular ibis breeding. These breeding events are stimulated by periodic inundation, and their successful completion is dependent on duration, i.e., the slow recession of floodwaters or the occurrence of follow-up flooding. River regulation and the extraction of off-allocation water is considered to be responsible for the loss of some inundation events, the more rapid recession of floodwaters and a reduction in follow-up flood events. To ensure completion of bird breeding events, off-allocation diversions are restricted and a Contingency Allocation is used to extend the period of inundation. Contingency Allocations for waterbird breeding events have been defined for Booligal Rookery (11 GL) and Lake Tarwong (9 GL) (Denham and McCauliffe, 1994). Use of these

ENVIRONMENTAL WATER REQUIREMENTS FOR WETLANDS 37

allocations is dependent upon the initiation of bird breeding and natural flows (Allan and Lovett, 1997; DLWC, 1998).

There is also an unregulated flow policy, similar to the “off-allocation” rules of the Macquarie Marshes Water Management Plan. The priorities of this policy include the provision of water to sustain fish populations and wetland ecosystems. Assessments of wetland requirements are made when unregulated water becomes available (Allan and Lovett, 1997). The health of plant communities has been considered in terms of the management of allocations to Booligal Wetlands and the Great Cumbung Swamp (DLWC, 1998).

38 ENVIRONMENTAL WATER REQUIREMENTS FOR WETLANDS

2. LITERATURE REVIEW

Lake Merreti and Lake Woolpolool (Chowilla Floodplain, South Australia) The Chowilla floodplain is located on the lower Murray River and is recognised under the Ramsar Convention. The lower Murray is intensively regulated, with flows controlled by the operation of weirs, barrages near the river mouth and releases from the storages of on the River Murray and Menindee Lakes on the Darling River. The flow regime is now more stable, with higher summer flows and a reduced frequency of overbank flows (Jensen, 1994, Allan and Lovett, 1997). Floodplain inundation has been reduced, and the proportion of permanent wetlands has increased (Jensen et al., 1994). Strategic manipulation of weir levels and releases from the storage lakes have been suggested as mechanisms for returning the floodplain wetlands of the Lower Murray to their pre-development water regime (Jensen, 1994). The water regimes of lakes on the Chowilla floodplain, including Lake Merreti and Lake Woolpolool, have been managed for environmental purposes (Jensen, 1994; Jensen et al., 1994). Flushing flows have been re-instated, with the aim of enhancing wetland habitat value and maximising biodiversity (Jensen et al., 1994).

Lake Merreti is a freshwater lake fed by backwater creeks of the River Murray. As a result of river regulation, the water regime of Lake Merreti had become more permanent, with less frequent flood events. A regulator had been installed for the purpose of using the lake for water storage. Since 1982 a regulator has been used to protect ibis breeding and create temporary fringe flooding around the edges of the lake (Jenson et al., 1994).

Lake Woolpolool lies to the west of Lake Merreti. The water regime of this lake is also managed for the purposes of reducing surface salinisation, to encourage tree regeneration and for the provision of waterbird breeding and feeding habitat (Jensen, 1994). A control valve is operated to allow water

ENVIRONMENTAL WATER REQUIREMENTS FOR WETLANDS 39

inflow when surplus flows are available (Jensen et al., 1994). Localised regeneration of river red gums and successful waterbird breeding events have occurred since the implementation of this water management strategy (Jensen, 1994).

Lakes Merreti and Woolpolool are examples of small wetlands in a highly disturbed system where a return to pre-development water regimes by manipulating levels with regulators is possible (Roberts et al., 2000). On a larger scale, such as the Chowilla floodplain wetlands as a whole, consumptive demand for water is likely to be too high to allow a return to a pre- development water regime.

Barmah-Millewa Forest (Victoria/NSW) The Barmah-Millewa Forests are located in Victoria (Barmah Forest) and in NSW (Millewa Forest), along the floodplains of the Murray and Edward Rivers (Directory of Important Wetlands website). They are the largest river red gum forests in the world, occupying a total area of approximately 60 000 ha (MDBC, 1990). Habitats include swamps, moira grasslands, marshes, rushlands, open water, streams, black box forest and red gum forest (Allan and Lovett, 1997). The plant associations are related to flooding frequency and duration; reeds, rushes and grass plains occur in areas most frequently flooded, while box forests occur in areas rarely or never flooded (Bren, 1992). The Forest is considered to be of special significance due to its size, the variety of communities, its high productivity, waterbird breeding and the presence of threatened and endangered species (Directory of Important Wetlands website).

The hydrology of the Forests has been altered as a result of river regulation. Prior to construction of the Dam in 1934, the water regime was

40 ENVIRONMENTAL WATER REQUIREMENTS FOR WETLANDS

2. LITERATURE REVIEW characterised by high flows in winter and spring, and low flows in summer and autumn (Bren, 1992, Allan and Lovett, 1997, Directory of Important Wetlands website). Since regulation, the rivers have been used to transmit water to downstream users. To achieve this, summer flows are maintained at about maximum channel capacity. Immediately after the was commissioned in 1934, these high summer flows were associated with large losses of water into the forest via effluent streams, which resulted in the deaths of some red gums. Regulators were built at the junction of many effluent streams to prevent these flows (Bren, 1992). However there is still some summer flooding in the Forests as a result of increased river levels during the irrigation (Atkins, 1993). Rain rejection flows occur when allocations delivered are not used by irrigators due to localised summer rain (Barmah- Millewa Forum and MDBC, 2000). These flows are diverted into the Forests at the Gulf Regulator to avert flooding of the Barmah township. This diversion affects wetlands in the Gulf region (Atkins, 1993). However, much of the Forests is affected by reduced flooding because of diversion of water for irrigation (Directory of Important Wetlands website). It has been estimated that prior to regulation, 70% of the Forest was flooded for an average of 2.9 months in 78% of years. Since dam construction, this degree of flooding only occurs for an average of 1.3 months in 37% of years.

Ecological effects of these alterations to the water regime include changes in species compostion of rushlands, grasslands and forests, reduced tree health and growth rates and reduced waterbird breeding (MDBC, 1990; Bren 1992; Atkins, 1993). Invasions of giant rush, and of river red gums into moira grasslands is considered to be an effect of summer flooding. The area of moira grasslands has been reduced (Bren, 1992).

ENVIRONMENTAL WATER REQUIREMENTS FOR WETLANDS 41

The Murray-Darling Basin Commission used to provide water for environmentally sensitive areas on an ad hoc basis (Barmah-Millewa Forum and MDBC, 2000). Small volumes of water were periodically released to meet waterbird breeding requirements in summer and fish requirements in winter, based on the knowledge of local interest groups (Kinhill Engineers, 1988). Now water management is based on a more formal approach (Barmah-Millewa Forum and MDBC, 2000). The forest has been divided into management units defined according to water regime patterns or requirements. These units are managed independently. The characteristics of the pre-regulation flow regime deemed most beneficial ecologically are included in the managed regime as far as possible. This is achieved through measures including an environmental water allocation of 100 GL per year from the Hume Dam, and the refinement of procedures for ordering irrigation water from Hume Dam and Yarrawonga Weir. Stakeholders are represented through the Barmah-Millewa Forum. The Barmah-Millewa Forest is an example of a large wetland system with a water regime profoundly altered by river regulation with a formal environmental water allocation.

42 ENVIRONMENTAL WATER REQUIREMENTS FOR WETLANDS

2. LITERATURE REVIEW

Groundwater-fed wetlands As consumptive pressure on surface water resources has increased, irrigators in some regions have turned to groundwater resources (Allan and Lovett, 1997). In regions such as the Murray-Darling Basin, very little is known about the contribution of groundwater to wetland hydrology, and it is virtually ignored in much of the literature concerning environmental water allocations (Hatton and Evans, 1998). In a review of groundwater-dependent ecosystems, Hatton and Evans (1998) concluded that the Great Artesian Basin and the Swan Coastal Plain lakes were examples of groundwater-dependent ecosystems which are well-understood. Examples of groundwater-dependent ecosystems which are little-understood include the Cape Range karstic ecosystem at Exmouth, relict streams in the Central Australian Ranges, saline discharge lakes of the Western Murray Basin, paperbark swamps in the tropical far north, spring ecosystems of the Pilbara and coastal lakes of dunes and beachridge plains in eastern Australia.

In some cases the effect of human impacts on groundwater-dependent ecosystems is reduced water quantity (eg extraction), while in others the effect is super-abundance (eg clearing). Reducing the availability of groundwater may lead to a gradual decline in the spatial extent of the ecosystem, or the health of vegetation. In other cases, thresholds may exist where after a certain point the entire ecosystem is destroyed (Hatton and Evans, 1998).

ENVIRONMENTAL WATER REQUIREMENTS FOR WETLANDS 43

Lakes of the Gnangara Mound (Swan Coastal Plain, Western Australia)

The Gnangara Mound is a large unconfined surface aquifer. It extends for approximately 2 200 km2 under the Swan Coastal Plain north of Perth, Western Australia. Due to the , with hot dry summers and mild wet winters, recharge of the aquifer primarily occurs in winter. Land use above the aquifer includes state forest, national park and crown land. Of this, pine plantations cover 20 000 ha, while the remainder consists largely of natural bushland. Groundwater is abstracted from the aquifer for water supply for Perth, resulting in reduced recharge. Recharge is also reduced by the pine plantations; the extent depending upon the density of the pines. Clearing for urbanisation, in contrast, results in increased recharge. Variations in rainfall also affect recharge (WAWA, 1995; Allan and Lovett, 1997).

The mound supports over 200 wetlands, most of which are surface expressions of the aquifer (WAWA, 1995). The water regimes of these wetlands are therefore affected by extraction, changes in land use and rainfall variability. Other groundwater-dependent ecosystems which may be threatened by water extraction include woodland and the cave pool fauna of Yanchep National Park. Concern regarding the environmental impact of groundwater extraction from the Gnangara Mound led to the determination of environmental water requirements for the wetlands (Figure 4).

44 ENVIRONMENTAL WATER REQUIREMENTS FOR WETLANDS

2. LITERATURE REVIEW

Early 1970s groundwater abstraction began on the Gnangara Water Mound

1988 ERMP (Environmental Review and Management Program) Prepared by WAWA

1988 ERMP Assessed by EPA and approved by government. Increased abstraction allowed subject to meeting the following environmental conditions • Absolute and preferred minimum water levels for wetlands • Limits on private abstraction • The introduction of a management and monitoring program • Administration mechanisms for agency interaction on groundwater management • Pine plantations would be managed by CALM with the objectives of achieving and maintaining their water use at a level that is no more than that of the pre-existing vegetation

WAWA 1991 Catchment Protection Policy

Research program focussed on EPA Environment Protection (Gnangara Mound Crown Land) Policy • Wetland ecology • identified beneficial uses • Evaluating, mapping and • identified activities that can degrade groundwater, native classifying wetlands vegetation or wetlands

WAWA expanded and revised monitoring program, to include • groundwater levels • terrestrial vegetation • wetland vegetation • wetland invertebrates

New information A small number of breaches of 1993 allocation of regarding groundwater water level criteria had occurred, in groundwater to Public requirements of both the duration below the private users had schemes had ecosystems preferred minimum level and the exceeded the total exceeded the absolute minimum level quota quota

1993 Government review of the original Environmental Conditions

Section 46 EPA Concepts of EWRs and EWPs: EWR: Environmental Water Requirements EWPs: Environmental Water Provisions Selected 13 wetlands on the Gnangara Mound and determined EWRs and EWPs for these. Water Corporation switches off bores as directed by the Water Resources Commission. New management and monitoring program

1996 EPA approves EWR and EWP process ENVIRONMENTAL WATER REQUIREMENTS FOR WETLANDS 45

Figure 4. History of the determination of environmental water allocations for wetlands of the Gnangara Mound

Groundwater extraction from the Gnangara Mound began in the early 1970s. In 1987 the WA Water Authority prepared an Environmental Review and Management Program (ERMP) for the mound. This was assessed by the Environment Protection Authority and approved subject to Environmental Conditions being met. These included the maintenance of wetland water levels (absolute and preferred minimum water levels were set), limits on private groundwater allocation and the establishment of a management and monitoring program (EPA, 1996; Allan and Lovett, 1997).

In response, a major research program was established to examine the impacts of altered water regime on wetland plants (Froend et al., 1993) and aquatic invertebrates (Balla and Davis, 1993) and the use of wetlands by waterbirds (Storey et al., 1993). Research was also carried out on the classification of wetlands according to water quality and invertebrate community data (Davis et al., 1993) and wetland hydrology (Townley et al., 1993). The information from these research projects was used to determine wetland water requirements. The method of integrating the information from the research projects was to first identify the water regimes necessary to maintain fringing vegetation. These regimes were then compared with the requirements of other ecosystem components, such as aquatic invertebrates and waterbirds (WAWA, 1995). The wetland vegetation research indicated that the effect of permanently lowered water levels would be a shift of the fringing vegetation down-gradient (Froend et al., 1993). In applying this knowledge, the water regimes identified were

46 ENVIRONMENTAL WATER REQUIREMENTS FOR WETLANDS

2. LITERATURE REVIEW those necessary to maintain the current vegetation distributions, avoiding the down-gradient shift (WAWA, 1995).

Vegetation requirements included a minimum 3 months dry period per year, for tree health, and a minimum inundation depth of 0.8 m to support the sedge Baumea articulata. The requirements of vegetation were considered in conjunction with the average seasonal range of the wetland to determine maximum and minimum water levels. Invertebrate requirements of a minimum period of four months per year of water in seasonal wetlands were incorporated into the determination of required water levels. This represents the time required for invertebrates to complete their life cycles. Maximum drying rates of 0.02 m/day were set to enable invertebrates that lay their eggs in the flooded fringing vegetation to complete their life cycles before the wetland dried (WAWA, 1995). The invertebrate research recommended that the maintenance of a mosaic of seasonal & permanent wetlands would meet the requirements of different species. Where water was pumped into wetlands to compensate for extraction, it was recommended that it be done in spring if peak water levels had not flooded the fringing vegetation. This follows the naturally occurring water regime where maximum water levels occur in spring (Balla and Davis, 1993). For waterbirds, management on a wetland-by-wetland basis was deemed necessary as no general relationships were found (WAWA, 1995).

Environmental Water Requirements (EWR) were set for 13 wetlands, including both permanently inundated and seasonal waterbodies. Environmental Water Provisions (EWP) were the actual water allocations for the environment; these were determined by considering social and economic factors as well as environmental needs. The requirements are sometimes met artificially, by pumping groundwater into the wetland. There is concern that artificial recharge of specific wetlands conflicts with the concept of setting

ENVIRONMENTAL WATER REQUIREMENTS FOR WETLANDS 47

EWRs for representative wetlands as a basis for maintaining all wetlands of the mound. However it is considered appropriate, due to the high demand for water, provided that the artificial water levels are not significantly higher than regional water levels (Allan and Lovett, 1997). The mechanism of setting EWRs and EWPs for 13 representative wetlands was approved by the EPA (EPA, 1996).

Management objectives and performance indicators are set for each of the 13 representative wetlands. These vary between the individual wetlands, reflecting their particular ecological and social values. Examples include:

Coogee Springs

maintenance of the diversity of aquatic invertebrate fauna,

maintenance and if possible enhancement of the vegetation, and

maintenance of water for bird breeding.

Lake Joondalup

maintenance of the landscape amenity value (WAWA, 1995).

Performance indicators relate closely to the management objectives and allow the management regime to be assessed (WAWA, 1995).

Twin Swamps (WA)

The water regime of Twin Swamps, on the northern Swan Coastal Plain is managed to meet the requirements of the western swamp turtle (Pseudemydura umbrina), an endangered species with a very restricted distribution. Duration of flooding may have been reduced from pre-development levels at Twin Swamps by groundwater extraction, clay extraction, changes in landuse and rainfall variations (DCE, 1983). The turtle requires a minimum period of

48 ENVIRONMENTAL WATER REQUIREMENTS FOR WETLANDS

2. LITERATURE REVIEW

inundation to allow sufficient feeding of aquatic invertebrates to enable it to survive summer aestivation and to breed successfully. The precise water regime requirements of this species have been calculated as a minimum of 0.2- 0.3 m from late June to early/mid November (Burbidge and Kuchling, 1994). These requirements are met by groundwater pumping (ANCA, 1996).

Great Artesian Basin Mound Springs (SA, NSW, Qld)

In the Great Artesian Basin protection of the water resource is being achieved through a reduction of wastage. Measures to reduce wastage of water include the capping of bores and the replacement of open earth drains with piped irrigation systems. While these activities are largely motivated by the need to maintain pressure for bore extraction, they also protect the mound springs. Currently 95% of the resource is being wasted due to the use of uncontrolled bores and open earth drains, therefore a change of practices could drastically reduce use. This has occurred to some extent already (Reyenga et al., 1998). The new Water Management Plan for Cooper Creek in Queensland specifically includes the protection of wetlands, and the maintenance of variable and seasonal flow patterns as environmental principles. It provides protection for underground water supplies. A recharge area for the Great Artesian Basin lies within the Cooper Creek catchment, as does the Aramac spring complex (WAMP, 1999). The Olympic Dam minesite near Roxby Downs in South Australia extracts artesian water. Monitoring of water levels and biota is carried out to assess potential impacts of this extraction (Jensen et al., 1998).

Conclusion

The case studies documented here reveal that emphasis has been placed on different ecosystem components in the determination of environmental water allocations to wetlands. Focus has been on reducing salinity (Kerang Lakes),

ENVIRONMENTAL WATER REQUIREMENTS FOR WETLANDS 49

protecting a single species (Twin Swamps), re-instating seasonality (Lake Merreti) and protecting water bird habitat (the Macquarie Marshes and wetlands of the Lachlan Valley). The determination of environmental water allocations for wetlands of the Gnangara Mound was made by examining the water regime requirements of several ecosystem components.

In practice the determination of environmental water allocations has not been a one-off exercise but has involved fine-tuning of allocations over time (illustrated in Figures 3 and 4), demonstrating the role of adaptive management. Increased extraction over time results from an increase in the consumptive demand for water, resulting in an increase in the environmental impacts. The use of environmental water requirements and performance indicators, as used in the management of the Gnangara mound, enables evaluation of the environmental water allocation. Future development and use of models such as the Environmental Flows Decision Support System (Young et al., 1999) may assist in the determination of modified flow regimes, but models are likely to be specific to particular types of wetlands and geographical locations. Models could be used to predict drying of wetlands which negatively affects waterbird breeding events, resulting in more strategically managed environmental water allocations.

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3. COMPARISON OF METHODS

3. COMPARISON OF METHODS FOR THE DETERMINATION ENVIRONMENTAL WATER ALLOCATIONS FOR WETLANDS

Introduction Approaches to determining the environmental water requirements of wetlands can be divided into two main methodologies; hydrology-driven and ecology- driven (Gippel, 1996). The hydrology-driven approach involves first the description and then the restoration of the historic (pre-disturbance) water regime of the wetland. It is assumed that the biota is adapted to the pre- disturbance water regime and that the restoration of this regime will result in a healthy ecosystem. Where consumptive demand is high, a return to pre- development conditions will not be possible. In these cases the hydrology- driven approach aims to restore to the wetland a water regime which resembles the historic regime as much as possible (McCosker, 1998).

The ecology-driven approach involves the determination of the water regime requirements of the existing or preferred biota, and the provision of that regime (Gippel, 1996). Ecology-driven approaches include a methodology developed by Roberts et al. (2000) for floodplain wetlands based on plant water requirements, and the determination of water requirements of wetlands of the Gnangara Mound on the Swan Coastal Plain in Western Australia, based on the requirements of wetland flora and fauna (WAWA, 1995). The strengths and weaknesses of both hydrology- and ecology-driven approaches were assessed by examining their application in recent case studies.

ENVIRONMENTAL WATER REQUIREMENTS FOR WETLANDS 51

Methodologies for determining environmental flows for rivers were also considered. These include historic discharge, or “rule of thumb” methods, habitat analysis methods which determine useable habitat by transect analysis and flow simulation, and instream habitat modelling, which determines habitat preference curves for species and models how changes in discharge affect habitat availability (Swales and Harris, 1995). Of these methodologies, historic discharge and habitat analysis methods may be considered hydrology-driven, while instream habitat modelling may be considered ecology-driven.

Habitat Analysis Methodology (Burgess and Vanderbyl, 1996) is a holistic method (Arthington, 1998) developed for riverine systems, It is based on the estimation of flows required to maintain all types of habitat. Wetlands are one of several habitats considered within this methodology (Burgess and Vanderbyl, 1996). Holistic approaches involve the incorporation of the essential features of the natural flow regime into the modified regime (Arthington and Pusey, 1992). Essential features of a flow regime include the perenniality or intermittency of flow, the seasonal distribution of flows, periods of no flow, and variability of flows at various time-scales (Arthington, 1998). Historical flow records from the period prior to regulation are analysed to identify the essential features of the river in question. Arthington and Pusey (1992) suggested that holistic methods are appropriate for wetlands.

In addition to these methodologies, modelling of the ecological effects of various environmental water allocations may also provide useful information for management. The Environmental Flows Decision Support System (EFDSS) developed by Young et al. (1999) is a software tool based on expert knowledge of the relationship between river flow and environmental condition. Drawing upon holistic methodologies (Arthington et al., 1998), it enables the ecological effects of proposed flow scenarios to be examined (Young et al., 1999). This

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3. COMPARISON OF METHODS

approach extends the hydrologic approach to incorporate ecological considerations. It may be particularly useful in the trade-off process between various water users (Young, 1999).

ENVIRONMENTAL WATER REQUIREMENTS FOR WETLANDS 53

Hydrology-driven approaches General The pre-development water regime of wetlands may be determined through the use of historical data where this is available, or through modelling. Significant elements of the pre-development water regime include the quantity, timing, duration and frequency of inundation (McCosker, 1998). This information may be gained from historical hydrological data or from modelling. While hydrology-driven methodologies for the determination of environmental flows overseas have tended to focus on the maintenance of minimum flows, in Australia the importance of maintaining natural variability is considered critical (Arthington, 1998). Management of wetland environmental water requirements may involve the reinstatement of seasonal or ephemeral water regimes (eg Mudgway et al., 1996).

A limitation of the hydrology-driven approach is the lack of a direct focus on current ecological values. Where hydrological disturbance has occurred in the more distant past the vegetation may have inalterably changed as a result of the disturbance, and the historical water regime may not be relevant to the existing biota (Bennett and McCosker, 1994). The biota may also have changed due to factors not directly related to the hydrological disturbance, for example, alteration to the , cattle or climate change. In these cases return to the pre-development state may not be possible without a high level of intervention, as seed banks have a finite life span (Brock, M., 1998).

Advantages of hydrology-driven approaches in riverine ecosystems include low cost (Growns, 1998), and the lack of reliance on detailed knowledge of the water requirements of wetland biota. However they are considered to have a low level of defensibility in trade-off situations (Growns, 1998). They are not

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3. COMPARISON OF METHODS

amenable to predictive modelling of the consequences of a lack of compliance with the determined environmental water allocations.

Pusey (1998) argues that the question being addressed by environmental flow allocations in rivers is “how much water can be harvested from a river without ecological damage?” The question for wetland environmental water allocations may be defined as “how much can the water regime deviate from pre- development conditions without ecological damage?” Where it is not possible to return to the pre-disturbance water regime because of consumptive water allocations, there is little basis for the determination of the degree of allowable deviance without reference to the water requirements of the biota. Hydrology- driven approaches in river environmental flow determination have been based on percentages of the “natural” flow (Arthington, 1998). This may not be valid unless the determination is based on biological data as the response of biota to variations in water regime is rarely linear (Roberts et al., 2000). Thresholds at which ecological damage occurs can only be determined through detailed analysis of the needs of biota.

ENVIRONMENTAL WATER REQUIREMENTS FOR WETLANDS 55

Examples of hydrology-driven approaches

Hydrology-driven resource management approach Knights and Fitzgerald (1994) propose an approach to riverine environmental flow determinations which is hydrology-driven and incorporates socio- economic impact data (Figure 5). Although it uses ecological data, it is hydrology-driven in that possible management measures are modelled in terms of their divergence from the pre-development water regime, implying that the objective of management is to re-instate the pre-development water regime to the extent that socio-economic constraints allow. They argue that their Determine the hydrological divergence approach is more pragmatic than ecology-basedfrom the approaches. pre-development water regime.

Ecosystem impact data

1. Generic relationships hydrology and hydraulics and habitat, function, species Identify possible hydrologic management/ mitigation measures

2. Site specific relationships hydrology and hydraulics and habitat, function, species Model hydrologic divergence of above options

Sensitivity analysis of management options

Environmental risk vs consumer risk

Socio-economic impact data

cost reliability and restrictions Non-hydrologic and water availability mitigations

Trial / monitor review report adjust

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3. COMPARISON OF METHODS

Figure 5 Hydrology-driven resource-management approach (Knights and Fitzgerald, 1994, p.136)

Hydrology-driven approach to the determination of environmental water requirements of the Gwydir wetlands Bennett and McCosker (1994) used computer simulation to determine the pre- development water regime of the Gwydir Watercourse. The results indicated that inundation of 20 000 ha occurred in 85% of years. A common duration of more than 30 days was suggested. The approach of this hydrology-driven analysis supported estimates of plant water requirements (McCosker and Duggin, 1993: Bennett and McCosker, 1994). The quantity of water required to achieve inundation of areas of water couch and rushes was determineded using the following two methods.

1. calculation of a water budget (McCosker and Duggin, 1993), and

2. the establishment of the relationship between streamflow and area inundated using and streamflow records (Bennett and McCosker, 1994).

The two methods produced similar results.

Ecology-driven approaches General A significant advantage of ecology-driven approaches is that they directly address the current ecological values and issues facing the wetland, for example, use by waterbirds, presence of endangered species or communities, tree deaths associated with altered hydrology and the presence of invasive

ENVIRONMENTAL WATER REQUIREMENTS FOR WETLANDS 57

species. This means that allocations developed using these approaches should be easily defensible in trade-off situations. Ecology-driven approaches enable conceptual models to be developed which indicate the consequences of various water regime scenarios for wetland biota. Obligations associated with Ramsar- listing may be directly addressed, as water regimes can be managed to meet the breeding requirements of waterbirds (see Briggs and Thornton, 1999). Hydrological elements of key significance may be identified through an examination of the requirements of biota, for example, duration and frequency of inundation and depth.

A disadvantage of ecology-driven approaches is the lack of information regarding species requirements. Additional research may be required where existing information is inadequate (Roberts et al., 2000). A limitation is that existing knowledge of plant water requirements is usually based on observation rather than experimentation (Bennett and McCosker, 1994). Longer term studies are required to determine the effects of extreme floods and droughts. Methodologies based on an ecology-driven approach generally involve the examination of historical water regime data (eg Roberts et al., 2000, Figure 6), but differ from hydrology-driven approaches in that they are characterised by ecology-based management objectives. In an adaptive management framework, management objectives can be framed as testable hypotheses, which monitoring programs can be designed to test (Chapman and Underwood, 1997). For example, if the management objective is to maintain healthy Melaleuca, and a strategy is devised to provide a water regime to achieve this objective, monitoring of water levels and Melaleuca health should provide an indication of both whether or not the managed water regime is achieved, and whether the objective is achieved. The results of hydrological and biological monitoring programs can therefore provide further information regarding species response to changes in water depth.

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In environments where it is not be possible to return to a pre-disturbance state, ecology-driven approaches may be particularly useful. Roberts et al. (2000) consider that restoration to a pre-disturbance state may be achievable in small, discrete wetlands, with the aid of regulators, but may not be possible for floodplain wetlands. Chapman and Underwood (1997) argue that restoration may not be a suitable objective for wetlands affected by urban development.

ENVIRONMENTAL WATER REQUIREMENTS FOR WETLANDS 59

Examples of ecology-driven approaches

Objectives based on vegetation: methodology for estimating floodplain wetland plant water requirements (Roberts et al., 2000) Roberts et al. (2000) developed a methodology for the determination of environmental water allocations for floodplain wetlands based upon vegetation requirements (Figure 6). This methodology differs from the hydrology-driven approach of Knights and Fitzgerald (1994) and Mudgway et al. (1996) in that the management objectives are vegetation-related, and detailed analyses of plant water regimes are required. Plant water regimes are defined as the pattern of water level changes required for the maintenance and regeneration of plant species. Longer-lived woody vegetation is more likely to reflect historic water regimes than herbaceous vegetation, which responds rapidly to changes in water regime (McCosker, 1998). Effects of altered hydrology on floodplain vegetation include tree deaths (Roberts et al., 2000), invasion of the weed lippia (Phyla canescens) (McCosker, 1998) and river red gum ( camaldulensis) invasion of natural moira grasslands (Bren, 1992). This methodology has the advantage of a high level of defensibility during trade-off negotiations, as the determined environmental water allocations or requirements are ecologically based.

60 ENVIRONMENTAL WATER REQUIREMENTS FOR WETLANDS

3. COMPARISON OF METHODS

1. Describe ecology

hydrology uses and values

2. Set vegetation-related management objectives. Resolve internal trade-offs (within floodplain) eg grazing, conservation

------

3. Describe relationships between vegetation and water regime These stages are covered in detail in Roberts et al., (1999) 4. Determine the water regime required to achieve management objectives

------

5. Trade-off process with other water uses. Resolve external trade-offs eg with irrigators

6. Implementation

Figure 6. Methodology for estimating floodplain wetland water allocations based on the plant water requirements (adapted from Roberts et al., 2000). Other ecology-driven methodologies are examined in terms of the steps of this methodology (Figures 7 to 9).

ENVIRONMENTAL WATER REQUIREMENTS FOR WETLANDS 61

Framework of methodology used for Gwydir wetlands (McCosker and Duggin, 1993: Bennett and McCosker, 1994: Keyte, 1994) In the Gwydir wetlands, McCosker and Duggin (1993) examined plant water regime requirements. Four vegetation communities were identified, with their distributions dependent on different flood frequencies. Using a water budget, the quantity of water required to inundate two of these communities was calculated. There was an emphasis on control of the weed lippia (Phyla canescens), which had increased in abundance as a result of reduced flow to these wetlands (Figure 7).

1. Describe • hydrology • ecology

2. Set flora and fauna-related management objectives.

Implicit: maintain vegetation in good condition (restrict the invasion of the exotic lippia (Phyla nodiflora)). Provide suitable conditions for waterbird breeding

3. Describe relationships between vegetation and water regime. Four vegetation communities were considered; their distributions were defined in terms of frequency of inundation.

4a. Determine the water regime required to achieve management objectives in terms of frequency and duration of inundation. The water couch community was considered to require almost annual inundation for periods in excess of 30 days in order for it to compete with lippia.

4b Determined how the desired water regime could be delivered, ie the quantity of water required to achieve the desired inundation. This was done by using

• water balance calculations (McCosker and Duggin, 1993) and • remote sensing and upstream flow records to describe the relationship between upstream flow and the area inundated (Bennett and McCosker, 1994)

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3. COMPARISON OF METHODS

Figure 7. Determination of environmental water requirements of Gwydir wetlands (McCosker and Duggin, 1993; Bennett and McCosker, 1994)

Objectives based on vegetation, aquatic invertebrates and waterbird use: the determination of Environmental Water Requirements for Gnangara mound wetlands

A comprehensive ecology-driven methodology was used for the determination of Environmental Water Requirements and Environmental Water Allocations for the groundwater-fed wetlands of the Gnangara Mound on the Swan Coastal Plain, WA (Figure 8, WAWA, 1995). The water regimes of these wetlands are threatened by groundwater extraction. The hydrology of the wetlands and the water requirements of the wetland vegetation, aquatic invertebrates and waterbirds were examined in targeted research programs (see Balla, 1994; Balla and Davis, 1993; Davis et al., 1993; Froend et al., 1993; Storey et al., 1993; Townley et al., 1993, Figure 8). The water regime requirements of vegetation were first examined, with an objective of maintaining the existing distributions. These requirements were then compared with the requirements of aquatic invertebrates and waterbirds, for the determination of Environmental Water Requirements. Individual objectives and Environmental Water Requirements were set for each wetland, reflecting their particular environmental values (WAWA, 1995).

This approach has similarities with the Roberts et al. (2000) methodology for floodplain wetlands. It differs in that the requirements of wetland fauna were examined as well as those of vegetation. In wetlands where fauna are likely to have direct water regime requirements this approach may be more appropriate.

ENVIRONMENTAL WATER REQUIREMENTS FOR WETLANDS 63

Where different water regimes favour particular animal or plant groups at the expense of others, the preferred regime may be selected according to the ecology-defined management objectives of Step 2 (Figure 8). For example, in floodplain wetlands of some regulated rivers, the delivery of short duration floods could result in water reaching a comparatively large area of the floodplain, benefiting trees. The delivery of the same quantity of water in a longer duration flood will tend to benefit waterbird breeding (LWRRDC, 1997a). This is an example of a situation where a within-wetland trade-off is required (Step 2, Figure 8).

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3. COMPARISON OF METHODS

1. Describe ecology hydrology uses and values Wetlands mapped and classified according to aquatic invertebrate communities, etc

2. Set ecology-related management objectives (related to waterbirds, aquatic invertebrates and macrophytes, fringing vegetation, control of invasive species). Some management-related objectives are social rather than environmental in nature, eg maintenance of landscape amenity value through the imposition of an artificially permanent water regime. This step involves the resolution of internal trade-offs (within-wetland) eg conservation, landscape amenity

3. Describe relationships between vegetation, aquatic invertebrates, waterbirds and water regime.

4. Determine the water regime required to achieve management objectives Environmental Water Requirements were set for 13 wetlands. These were based on maintaining the existing distributions of vegetation, in terms of position and extent. This regime was then compared against the water regime requirements of wetland fauna, and adjusted where necessary. Water regime requirements were defined according to minimum and maximum water levels. Variability was incorporated by specifying the maximum numbers of years that certain criteria could be exceeded.

5. Trade-off process with social and economic factors. Represented by Environmental Water Provisions: the actual water allocations for the environment.

6. Implementation.

The use of performance indicators (related to the extent of sedge vegetation in the case of Lake Jandabup, for example) allows the testing of the determined water regimes. ie tests the hypothesis that the provision of the Environmental Water Requirements results in the maintenance of the existing extent of sedge vegetation. ENVIRONMENTAL WATER REQUIREMENTS FOR WETLANDS 65

Figure 8. Framework of the methodology used in the determination of the environmental water requirements of the wetlands of the Gnangara Mound, on the Swan Coastal Plain, WA.

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3. COMPARISON OF METHODS

Objective based on the protection of an endangered species: the western swamp turtle

Environmental Water Requirements of Twin Swamps were determined to meet the requirements of the endangered western swamp turtle (Pseudemydura umbrina) (Figure 9). This species has an extremely restricted distribution. The key water requirement identified was a minimum hydroperiod of 4 months per year. This is an example of a situation where the primary objective for the determination of a wetland environmental water allocation was the protection of a single endangered species.

1. The wetland together with the Ellen Brook , is identified as comprising the sole remaining habitat of the endangered western swamp turtle.

The hydrology of Twin Swamps and the water regime requirements of the western swamp turtle are described.

2. Management objective: the maintenance of a water regime which will allow the western swamp turtle to survive and breed.

3. Describe the relationship between the survival and breeding of the western swamp turtle and the water regime.

4. Determine the water regime required to achieve management objectives. (Minimum of four months of inundation required per year, to be achieved by pumping groundwater into the lake in dry years.)

5. Implementation

Figure 9. Determination of environmental water requirements for Twin Swamps, WA (Burbidge and Kuchling, 1994).

ENVIRONMENTAL WATER REQUIREMENTS FOR WETLANDS 67

68 ENVIRONMENTAL WATER REQUIREMENTS FOR WETLANDS

3. COMPARISON OF METHODS

Management for waterbirds Briggs and Thornton (1999) developed guidelines for the management of wetlands for waterbird breeding. A minimum inundation period of 5 to 10 months is required for waterbirds to complete breeding. Two waterbird breeding patterns in relation to water regime have been identified. Birds such as darters, cormorants, , white ibis and spoonbills generally nest at wetlands with permanent water in deeper, open areas; in contrast, ducks breed at wetlands which dry out completely between floods (Briggs and Thornton, 1999). The waterbird model of Young et al.’s (1999) EFDSS (discussed below) was based on the work of Briggs and others. Briggs and Thornton (1999) concluded that management of the water regimes of Eucalyptus camaldulensis wetlands for the optimisation of waterbird breeding should include flooding under nest trees for a minimum of 5 to 10 months, followed by drying before the next flood. Water should be allowed to remain permanently in deeper, open areas. In this way the requirements of both groups of waterbirds can be met.

Objectives based on waterbirds: Kerang Lakes (Hird and Johnson Swamp) An ecology-driven approach has been used for the determination of the water regime management of Hird and Johnson Swamps, part of the Kerang Lakes in Victoria (DCNR, 1990). The hydrology of these wetlands has been altered. Ecological and social values of waterbird habitat and duck hunting were identified. In the determination of a suitable water regime, the likely response of wetland plants and waterbirds was considered. The effects of water regime on invasive species such as Typha sp., water milfoil and carp were also considered. For example, an increase in the percentage cover of Typha sp. had occurred as a result of the altered hydrology. This was considered detrimental to both duck hunting and the preservation of waterbird habitat.

ENVIRONMENTAL WATER REQUIREMENTS FOR WETLANDS 69

The approach used in this study (DCNR, 1990) was to investigate two scenarios in terms of short- and long-term impacts on wetland flora and fauna, with an overall emphasis on maintaining habitat values that would enhance the value of the wetlands for waterbirds and duck-hunters. One scenario was the imposition of a permanent water regime, and the other was to allow the wetlands to dry out between summer and autumn every 3-4 years. The latter option was considered to provide the best long-term waterbird habitat.

Environmental water allocations for the Kerang Lakes were calculated using water and salt balances (Mudgway et al., 1996). Objectives were to reduce the salinities by flushing permanent wetlands, and to provide a period of drying for semi-permanent wetlands. An environmental water allocation of 27 600 ML per year was available for this. It was deemed that the period of drying could be either three to four months every year or alternatively a period of one year in every five years. The option of one year every five years was selected on the basis of being more “natural” and easier to achieve through a rotation system.

Habitat Analysis Methodology (Burgess and Vanderbyl, 1996)

Habitat Analysis Methodology was developed in Queensland, for the Water Allocation and Management Planning Initiative (Arthington et al., 1998), for the determination of riverine environmental flow allocations. A “panel of experts” approach, it is based on estimated flows required for the maintenance of all types of habitat. It differs from the ecology-driven approaches previously described in that it is based on meeting the requirements of habitats rather than species. Generic habitats, such as riffles, wetlands and floodplains are first identified, then the flows which will maintain those habitats are determined (Burgess and Vanderbyl, 1996). Habitat Analysis Methodology involves an

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3. COMPARISON OF METHODS

examination of historical flow records to describe the pre-development flow regime, and does not include guidelines for the determination of plant water requirements (McCosker, 1998).

An adaptation of this approach for wetlands is given in Figure 10. It differs from Habitat Analysis Methodology in that the water requirements of wetland biota are specifically examined. This adaptation is compatible with ecology- driven approaches. The determination of wetland plant water regimes frequently involves the consideration of plant water requirements in terms of generic habitat types. For example, in the Gwydir wetlands, different wetland habitat types, characterised by particular vegetation communities, were considered in relation to water regime (Figure 7, Step 3; Keyte, 1994). Areas of water couch and rushes (the core wetland areas) were examined for the calculation of the quantity of water required to achieve inundation (Figure 7, Step 4a and Keyte, 1994). Young et al.’s (1999) Environmental Flows Decision Support System (EFDSS) (Section 5) considers different habitats of the riverine environment. These wetland habitats, based on plant communities with clonal growth, are likely to be dynamic; their distributions moving up- or down-gradient in response to water level changes (Froend et al., 1993).

1. Identification of generic habitat types within the wetland(s), based on depth and/or frequency/duration of inundation. Usually these will be based on vegetation associations. eg 1. zone of open water/ submerged aquatics 2. zone of emergent macrophytes 3. fringing trees

2. Determination of water requirements of biota within each habitat, in terms of depth, duration and timing.

3. Determine a water regime that will best meet the needs of biota in all habitats.

ENVIRONMENTAL WATER REQUIREMENTS FOR WETLANDS 71

4. Development of water management strategies to meet these requirements.

5. Development of a monitoring strategy to check the effectiveness of the above water management strategies.

Figure 10. Adaptation of Habitat Analysis Methodology (Burgess and Vanderbyl, 1996) for wetlands.

Modelling

Environmental Flows Decision Support System (EFDSS) (Young et al., 1999) The EFDSS is a computer-based numerical model which enables the relationship between flow regimes and ecological condition to be explored. Data from computer-simulated river flows are used to drive models of environmental condition (Young, 1999). Designed for the regulated rivers of the Murray-Darling Basin, it includes the wetlands associated with rivers. A model of floodplain hydrology (Young et al., 1999) is included. Zones and locality types are recognised; four of the six locality types are ‘off-river;’ billabongs, wetlands, riverine lakes and floodplains, and as such fall within the scope of this study. The impact of different scenarios (modelled flow regimes) on the ecology can be examined.

The incorporation of some aspects of a hydrology-driven approach is evident as ‘natural’ and ‘current’ scenarios are always included. The ‘natural’ scenario is the conditions that would exist in the absence of regulation or diversion. It is essentially an ecology-driven approach in that it is based on information regarding the response of biota to changes in flow regime. In the case of fish

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3. COMPARISON OF METHODS

and waterbirds, groups of species with common water regime requirements are defined.

Decision support systems such as this could be designed specifically for non- riverine wetlands. This approach may be useful in trade-off situations, as the effect of less than optimum water regimes on ecological condition will be demonstrated. It may be a particularly useful tool where consumptive pressure on water resources is strong as a return to pre-development water regimes is unlikely to be achievable in these situations (Young, 1999).

Conceptual modelling Conceptual modelling involves the examination of the ecological effects of various water regime scenarios. A generalised model of the responses of amphibious, submerged and terrestrial wetland plants to altered frequency of flooding, depth or extent of flooding, duration of flooding, and variability of flooding, as well as to more permanently wet and more permanently dry conditions has been developed by Brock and Casanova (1997). This model was then used in an analysis of the likely effects of water extraction on the wetlands associated with the (Brock, 1999). This is an example of the use of conceptual modelling.

Summary of methods

The major elements of the methods together with assessments of their respective advantages and disadvantages, are summarised in Table 2. A key disadvantage of hydrology-driven approaches is their lack of defensibility with respect to biotic conditions. Where consumptive demand for water is high, and there is either either adequate existing ecological knowledge or resources for targeted studies, ecology-driven approaches are likely to be most suitable. Multi-criteria analysis (Table 2) may be useful in the evaluation of

ENVIRONMENTAL WATER REQUIREMENTS FOR WETLANDS 73

environmental values and social and economic constraints, and in the resolution of trade-offs between different values and uses.

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3. COMPARISON OF METHODS

Table 2. Summary and assessment of methods for determining environmental water allocations for wetlands.

Approach Method Major elements Advantages Disadvantages

Hydrology-driven Determine the pre-development Does not require knowledge about The biota may have changed since water regime using any existing data the water requirements of wetland pre-development times due to causes and/or modelling. plants and not directly related to water regime; ie fire frequency, climate change. Attempt to restore this regime. Costs low Assumes the biota have linear responses to changes in water regime (Young et al., 1998). This is rarely the case (Roberts et al., 2000)

Difficult to justify the determined water regime in trade-off situations

Not amenable to the development of conceptual models Describe the divergence of the modified Knights and water regime from that of the Includes economic and social As above Fitzgerald (1994) predevelopment regime using considerations

Incorporates data on the relationship between water Authors propose that it is more multi-criteria regime and habitat, ecosystem function “workable” than ecology-driven analysis into an and species approaches. approach that is primarily data on the socio-economic impact of hydrology-driven changes to water availability,

Develop the preferred management option

ENVIRONMENTAL WATER REQUIREMENTS FOR WETLANDS 75

Approach Method Major elements Advantages Disadvantages Ecology-driven General Determine a water regime that will match Particularly useful where little pre- Is dependent upon knowledge about the requirements of preferred or existing disturbance hydrological information water requirements of wetland biota. biological communities, or those which is available. Requires a large research effort or used to exist (Gippel, 1996) detailed existing knowledge. Explicitly aimed at the protection of identified communities/species. However, many wetland species are Directly addresses the respective widely distributed (eg river red values of wetlands. gum), so knowledge from one wetland environmental water Allows focus to be placed on meeting allocation can be utilised for others the water requirements of in the same region. Monitoring data threatened/endangered species or (hydrological + biological) will add communities. to the knowledge of the water regime responses of wetland biota. Key hydrological elements of relevance to biota may be identified, eg hydroperiod, frequency of inundation.

Where invasion of exotic species is directly related to the flow regime, the problem can be specifically addressed.

The determined water regime should be defensible on ecological/biological grounds in trade-off situations.

Amenable to conceptual modelling

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3. COMPARISON OF METHODS

Approach Method Major elements Advantages Disadvantages

Ecology-driven Gnangara Determine the water requirements of Designed to protect existing Requires a large research effort or a existing or desired plants environmental values of wetlands large amount of existing knowledge with already disturbed hydrology, Set environmental water which were potentially threatened by requirements groundwater extraction.

Check against environmental water requirements of wetland fauna

Refine environmental water requirements to suit fauna if necessary

Roberts et al., Determine the water requirements of Can easily be adapted to include the Requires a large research effort or a (2000) existing or desired plants water requirements of fauna large amount of existing knowledge

Set environmental water Identification of surrogate species Does not address the water regime requirements (Roberts et al., 2000, p.36) may requirements of fauna. enable conceptual models to be devised.

ENVIRONMENTAL WATER REQUIREMENTS FOR WETLANDS 77

Approach Method Major elements Advantages Disadvantages

Holistic Approach Adaptation of An expert-panel approach. Hydrological monitoring (depth over Is dependent upon experts’ Habitat time) in conjunction with biotic knowledge of water requirements of (hydrology- driven, Analysis identify generic habitat types monitoring should allow the testing wetland biota. but incorporates Methodology of : ecological (Burgess and determine the water requirements The extent to which environmental requirements). Vanderbyl, of the biota of each habitat the experts’ assumptions about water requirements, provisions or 1996) for the response of the biota to allocations determined by expert Restore the wetlands develop water management change in water regime, and panels are defendable in trade-off essential elements strategies to meet those situations may vary, depending upon of the pre- requirements the effectiveness of the water the extent to which documentation is development water management strategies to meet provided to support the expert regime in order to develop a monitoring program to the requirements opinion (Growns, 1998). protect the biota check the effectiveness of the strategies Habitat-based Is not based around explicit objectives (the implicit objective is to return the wetland to the pre- development state).

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3. COMPARISON OF METHODS

Approach Method Major elements Advantages Disadvantages

Modelling Conceptual Focus on major habitats/ vegetation Generally requires the same modelling communities/ invasive species eg knowledge/ research base as ecology- Melaleuca recruitment or survival, driven methods. extent of Typha, etc. Incorporates water regime/ water balance Can incorporate variability

Computer Provides a framework for the Generally requires the same modelling eg gathering of data knowledge/ research base as ecology- EFDSS driven methods. (Young et al., Should result in a high level of 1999) defensibility of the environmental This model is specific to rivers of the water allocations in trade-off Murray-Darling. New models will situations need to be developed for other regions/ types of wetlands. Multicriteria List: May enable the evaluation of Will not necessarily provide water analysis environmental values environmental values and social and requirements/ allocations economic constraints socio-economic constraints May be used to identify key species/ knowledge of water requirements communities that are threatened by of fauna/flora water regime disturbance, for targeted research hydrology current Enables environmental water historical management of different wetlands to be compared, & differences justified

Useful for resolving internal and external trade-offs (Figure 3, Steps 2 & 5 )

ENVIRONMENTAL WATER REQUIREMENTS FOR WETLANDS 79

3. COMPARISON OF METHODS

Critical evaluation of methods A best practice methodology should address community aspirations, set ecological functions and ecosystem services as objectives, include objectives to enable the management to be evaluated, and not rely on a past set of ecological or hydrological conditions. The methodologies were therefore evaluated (Table 3) according to the following criteria:

Whether community aspirations can be structurally addressed in the process of setting objectives

Whether ecological functions and ecosystem services are set as objectives

Whether the method can be evaluated for its performance according to set objectives

Whether the method relies on a specified and known set of past ecological or hydrological conditions.

The Gnangara method was the only one fitting all of the above requirements, as its inclusion of seasonally drying in objectives incorporates ecological functions and ecosystem services into objectives. All three ecologically-driven methods may be evaluated according to objectives. Both the Gnangara and Roberts methods address community aspirations in the setting of objectives, through the identification of uses and values.

ENVIRONMENTAL WATER REQUIREMENTS FOR WETLANDS 81

Table 3. Critical evaluation of methods.

Have community Are ecological Can the method be Does the method rely Method aspirations been functions and evaluated for its on a specified and structurally ecosystem services performance known set of past addressed in the set as objectives? according to set ecological or process of setting objectives? hydrological objectives? conditions?

Knights and No No No Yes: hydrological Fitzgerald (1994) hydrology-driven resource management approach

Roberts et al. (2000) Yes: incorporated into No. Yes No uses and values in Objectives are based first step on vegetation health

McCosker and No No. Yes No Duggin (1993) Ojectives are based on vegetation health and waterbird breeding

Gnangara method Yes: incorporated Yes * Yes No into uses and values in first step

* The method included an emphasis on maintaining seasonal drying in wetlands deemed to have historically been seasonal wetlands. This was incorporated into objectives for individual wetlands. The determination of whether a wetland was seasonal or not was based on the life histories of invertebrates. Seasonality relates to ecosystem function and could be interpreted as part of the ecological character of a wetland.

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3. COMPARISON OF METHODS

Discussion A best practice methodology for the determination of environmental water allocations for a wetland or wetland aggregation is likely to incorporate elements of virtually all methods described here. In practice, determinations of environmental water allocations for wetlands generally depend on an assessment of pre-development and current water regimes, and the effects of altered hydrology on wetland vegetation, due to limitations of knowledge regarding vegetation water requirements (McCosker, 1998). A determination of environmental water allocations based on meeting vegetation objectives (Roberts et al., 2000 methodology) could be compared against the requirements of waterbirds (see Briggs and Thornton, 1999) or other wetland fauna (see Scott and Grant, 1997; Burbidge and Kuchling, 1994). The use of objectives based on identified values and the requirements of wetland biota is likely to provide a high level of defensibility for decisions regarding environmental water allocations.

Often wetlands are considered in terms of several different zones for the determination of water regime requirements of flora and fauna. The zones may be described in terms of vegetation communities with different water requirements (McCosker and Duggin, 1993; Keyte, 1994), or as vegetated areas compared with areas of open water (eg Briggs and Thornton, 1999). This aspect of Habitat Analysis Methodology is frequently incorporated into the analysis of wetland environmental water requirements.

The means of achieving the desired water regime is dependent upon the source of the water. In the case of the groundwater-fed wetlands of the Gnangara mound, the desired water regime is set using depth criteria. Groundwater pumping is controlled in such a way that these criteria are met (WAWA, 1995). For riverine wetlands, the relationship between wetland water levels

ENVIRONMENTAL WATER REQUIREMENTS FOR WETLANDS 83

and streamflow may be determined through the analysis of streamflow data and inundated area, using either aerial photos or remote sensing. Alternately water balance calculations may be used. The desired water regime may then be achieved through the control of dam releases, the operation of regulators, or through appropriate licensing of consumptive users.

Boulton and Brock (1999) noted that management strategies for Australian wetlands must be sufficiently flexible to incorporate the temporal and spatial variability that is a major characteristic of these systems. Natural variations in climate result in variable water regimes both within and between years. As a consequence the determination of environmental water allocations for a wetland is likely to be an ongoing process requiring adaptive management. The use of adaptive ecological management, where actions are monitored and used to successively refine further management approaches, will be a particularly important strategy for wetlands where changes need to be made when climatic conditions change (Boulton and Brock, 1999).

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4. FRAMEWORK

4. FRAMEWORK FOR ENVIRONMENTAL WATER ALLOCATIONS FOR WETLANDS

Framework The following framework (Figure 11) was developed from the review of contemporary methods and approaches (Sections 2 and 3 of this report). Elements of both the Roberts et al. (2000) and Gnangara (WAWA, 1995) methods have been incorporated into a stepwise approach.

ENVIRONMENTAL WATER REQUIREMENTS FOR WETLANDS 85

1. Characterise wetland in terms of 2. Identify • hydrology • uses • ecology • values • threats

3. Determine MANAGEMENT OBJECTIVES

4. Describe relationships between biota and water regime, focusing on relationships related to objectives

5. Determine the desired water regime to fulfil management objectives.

6. Refine desired water regime by examining various scenarios using conceptual modelling. Resolve trade-offs between all values and uses. Finalise the water regime requirements

8. Determine means of achieving the desired water regime 7. Set performance indicators in relation to biota.

9. Prescribe environmental water allocations to achieve the desired water regime

10. Implementation

Compare 11. Monitoring Compare against against performance environmental indicators water ll ti Results from Results from biological hydrological monitoring monitoring

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4. FRAMEWORK

Figure 11. Framework for the determination of environmental water allocations. Feedback loops are indicated by dashed lines.

ENVIRONMENTAL WATER REQUIREMENTS FOR WETLANDS 87

Step 1. Characterisation of wetland hydrology and ecology Step 1 involves the description of the hydrology and ecology of the wetland. Existing hydrological records are examined together with rainfall and evaporation data. It may be possible to identify the “essential elements” (sensu Arthington, 1998) of the pre-development water regime (such as the timing and duration of dry periods) from historical records. Alterations to the pre- disturbance water regime can be identified. Analysis of the water budget may be useful in determining human impact.

The water budget of a wetland may be examined in terms of the following equation:

∆S (t) = P + Qi + Gi - E - Qo - Go

where

∆S (t) = Change of wetland water volume over a defined period of time

P = Precipitation falling on the wetland over a defined period of time

Qi = Surface water flowing into the wetland over a defined period of time

Gi = Ground water flowing into the wetland over a defined period of time

E = Evapotranspiration over a defined period of time

Qo = Surface water flowing out of the wetland over a defined period of time

Go = Ground water flowing out of the wetland over a defined period of time

(Carter, 1986; LaBaugh, 1986; Bennett and McCosker, 1994).

The examination of water budget is usually difficult due to inadequate data (Gippel, 1993). The modelling of average monthly water levels rather than average annual water levels allows the consideration of the water requirements of wetland flora and fauna.due to the greater ecological significance of the

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4. FRAMEWORK

former. Gippel (1993) used a variety of estimation techniques to develop a continuous monthly model of the water level of a wetland.

ENVIRONMENTAL WATER REQUIREMENTS FOR WETLANDS 89

Existing data for wetland flora and fauna data are compiled, knowledge gaps are identified and surveys are carried out where necessary. Surveys may be focused on responses of the biota to changing water regimes. Examples include:

encroachment by weeds and terrestrial vegetation into areas previously characterised by wetland vegetation (see McCosker and Duggin, 1993);

changes in recruitment of woody vegetation (eg indicated by stands of either entirely juvenile or entirely mature trees) (see Bren, 1992)

tree deaths (see Roberts et al., 2000).

Wetland zones may be delineated based on vegetation communities (eg McCosker and Duggin, 1993), and the water regime of each zone described.

Descriptions of the ecology and the hydrology of a wetland form the basis of characterisation of the wetland. The ecological character is defined as:

“the structure and inter-relationships between the biological, chemical, and physical components of the wetland. These derive from the interactions of individual processes, functions, attributes and values of the ecosystem(s)”

(Ramsar web site)

Aspects of the ecological character include the intermittency, seasonality or permanency of the water regime, and the presence of particular vegetation communities and fauna. Dry phases give semi-permanent, seasonal or ephemeral wetlands their ecological character, as it affects many wetland processes (Crome, 1986, Balla and Davis, 1993, Bunn, 1999). Many wetland plants have specific requirements in terms of a dry phase, referred to as the inter-flood interval by Roberts et al. (2000) in relation to floodplain vegetation. In contrast, lack of drying is the the key to the ecological character of wetlands with permanent water regime such as mound springs.

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4. FRAMEWORK

ENVIRONMENTAL WATER REQUIREMENTS FOR WETLANDS 91

Step 2. Identify uses, values and threats Step 2 involves the identification of wetland uses, values and threats. Environmental and conservation values will be based on information collected in step 1 above. Examples include Ramsar listing, the presence of rare or endangered species, use of the wetland by migratory bird species covered by international conventions, and the relative rareness of the wetland type. Human uses and values may be related to Aboriginal significance, recreation, the appreciation of water views, grazing of lake beds and floodplains, and abstraction of water. The identification of threats is focused on those human activities which may alter the water regime.

Step 3. Determine management objectives Objectives may include meeting obligations associated with international conventions such as the Ramsar Convention. The Ramsar Convention requires “wise use” of wetlands, and an important aspect of “wise use” is the maintenance of ecological character (Adam, 1999, Ramsar web site). A general management objective is therefore to maintain the ecological character of the wetland (defined in step 1). The objective of maintaining a wetland’s ‘ecological character’ has some similarities with the objective of holistic approaches, that is, the identification and incorporation of the ‘essential features’ of the historic water regime into the modified water regime (Arthington, 1998). A difference is that ‘ecological character’ incorporates ecological as well as hydrological aspects. Both objectives are based on the concept that a degree of deviance from the pre-development state is acceptable within certain limits. They are compatible with the concept that ecological responses are frequently non-linear and often characterised by thresholds. This concept is generally accepted amongst wetland ecologists (Bunn, 1999).

Specific management objectives will be shaped by the identified uses, values and threats (Step 2). Management objectives may be based on vegetation (eg

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4. FRAMEWORK

Leitch, 1989, Roberts et al., 2000), waterbirds (eg Leitch, 1989; Briggs and Thornton, 1999), or other fauna (eg Leitch, 1989; Burbidge and Kuchling, 1994; WAWA, 1995). Resolution of trade-offs between conflicting values may be required. For example, the demand for year-round water views may conflict with the ecological values of a seasonally dry wetland (WAWA, 1995). Peat mining proved to be incompatible with water supply, heritage and habitat values in Wingecarribee Swamp in NSW (Tranter, 1999). The separation of these first three steps in this method (Figure 11) should result in a high degree of transparency and defensibility of trade-off resolutions.

Step 4. Describe the relationships between biota and the water regime The focus of this step is determined by the management objectives (Step 3) which require determination of wetland uses, values and threats (Step 2). Most attention will be placed on relationships between the water regime and significant communities or species; for example, if a wetland is significant due to the presence of waterbirds, the water regime requirements of waterbirds will be critical. These will include both direct water requirements (ie water regime requirements of the waterbirds) and indirect requirements (ie the water regime requirements of vegetation used by waterbirds).

For the examination of specific water regime requirements, wetland biota could be considered in terms of the following groups:

Algae

Submerged plants

Emergent plants

Trees and shrubs

Aquatic invertebrates

Fish

ENVIRONMENTAL WATER REQUIREMENTS FOR WETLANDS 93

Waterbirds

Other fauna (wetland , amphibians and mammals)

Water regime requirements of biota may be examined in terms of the identified wetland zones (Step 1).

Water regime requirements for both maintenance and recruitment of individual species need to be considered. Lack of knowledge regarding these requirements has been identified as an impediment to the determination of environmental water allocations (Allan and Lovett, 1997; Arthington et al., 1998; Roberts et al., 2000). Targeted research programs may be required where knowledge is inadequate (eg WAWA, 1995).

Biotic and hydrological monitoring (Figure 11, step 11) after the implementation of environmental water allocations can add to the existing knowledge of the effects of different water regimes on wetland biota. In turn this information can inform management (Figure 11). This adaptive management approach has been key to the development of environmental water allocations such as those of the Macquarie Marshes (Brock, P., 1998), and is seen as necessary due to lack of knowledge (Adam, 1997).

The water requirements of wetland biota may need to be considered over large spatial scales. Habitats can be assessed as interlinked systems if examined in terms of the needs of particular fauna (eg Scott, 1997; Scott and Grant, 1997). Fauna such as platypus and water rats move between rivers and wetlands (Scott and Grant, 1997) so the water regimes of both need to be examined. Many waterbirds travel large distances and utilise habitats provided by different wetlands; it is rare for them to use one habitat for all their needs (Briggs and Lawler, 1989). Water regime management for mobile fauna will therefore not

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necessarily involve the provision of permanently suitable habitat at a single wetland.

ENVIRONMENTAL WATER REQUIREMENTS FOR WETLANDS 95

Step 5. Determine the desired water regime The desired water regime is determined using the management objectives and the assessment of the requirements of the wetland biota. Characteristics of the desired water regime of wetlands may include:

amount (area inundated)

depth (minimum and maximum)

seasonality (whether inundation is permanent, seasonal or ephemeral)

season of maximum inundation

rate of rise and fall

size and frequency of floods

size and frequency of dry periods

duration of floods

duration of dry period

variability

(adapted from Roberts et al., 2000).

Step 6. Refine the desired water regime by examining various scenarios using conceptual modelling The use of conceptual modelling approaches such as EFDSS (Environmental Flows Decision Support System, Young et al., 1999; Pitcher, 2000) may assist the determination of the desired water regime. Trade-offs between different uses and values may be facilitated by modelling approaches. Mitchell (1999) considers that adaptive management is in essence “trial and error”, and argues that the impacts of errors can be minimised if any possible unwanted outcomes, as well as intended outcomes, are identified, and contingency plans are developed to deal with adverse impacts as soon as they are manifested. Both conceptual modelling and the use of numerical models may assist in the

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identification and prediction of outcomes. The scenarios from conceptual modelling may be compared against the management objectives determined in Step 3. The scenario which most suits the management objectives may then be selected.

Step 7. Set performance indicators in relation to biota Performance indicators are based on the management objectives. They are set in relation to biota, and reflect desired outcomes. They can include frequency and size of waterbird breeding events, health of vegetation, recruitment of plant species, relative abundance of particular invasive species and abundance of particular native species. They allow the success of the management strategy to be evaluated.

Step 8. Determination of the means of achieving the desired water regime The means of achieving the desired water regime depend upon the source of the water and the nature of the water regime disturbance. Dam releases, weir manipulations, restrictions to abstraction and the use of regulators could be required. In wetlands associated with rivers, the relationship between streamflow and area inundated may be determined through the analysis of streamflow data and remote sensing or aerial photograph interpretation (eg Bennett and McCosker, 1994). Water balance calculations may be extremely useful for many wetlands.

Step 9. Prescribe environmental water allocations to achieve the desired water regime Environmental water allocations are determined to achieve the desired wetland water regime to be met. For the groundwater-fed wetlands of the Swan Coastal Plain environmental water requirements were set in terms of frequencies of maximum and minimum depths of surface water (WAWA, 1995). Allocations for surface water dominated wetlands may involve the use of regulators, dam releases and abstraction restrictions. These allocations may be based on

ENVIRONMENTAL WATER REQUIREMENTS FOR WETLANDS 97

relationships determined in Step 8 between streamflow and area inundated or on the water balance calculations.

Step 10. Implementation This step involves the implementation of the allocations determined in Step 9. These may be modified in extremely wet or dry years.

Step 11. Monitoring Biological monitoring programs are planned to measure whether the performance indicators are met, while hydrological monitoring programs test if the desired water regime has been achieved. A feature of adaptive management is the viewing of management practice as an experiment, using hypotheses. Monitoring regimes are designed to test the hypotheses, and management is influenced by feedback from monitoring results (Chapman and Underwood, 1997). Over time, the data from both biological and hydrological monitoring programs should result in an increase in knowledge regarding the response of biota to changes in water regime.

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PILOT STUDIES

The framework descibed in Figure 11 was applied to four wetlands (Thomsons Lake, Bool Lagoon, Lower Gwydir Wetlands and Boggomoss Springs) to test or demonstrate its application to different wetland types.

Thomsons Lake Step 1. Characterisation of Thomsons Lake

Site Description Thomsons Lake is a shallow semi-permanent/ seasonal wetland on the Swan Coastal Plain, approximately 34 km south of Perth (Crook and Evans, 1981). It is part of the East Beeliar chain of wetlands which are expressions of the Jandakot Mound, an unconfined aquifer. Although the dominant source of water for Thomsons Lake is groundwater, there is some surface inflow from Kogolup Lake and from a drain to the south-east of the lake which passes through constructed wetlands. The lake is characterised by both high waterbird abundance and diversity (Storey et al., 1993), and areas of sedge vegetation (Directory of Important Wetlands web site).

Hydrological data The following information regarding the water regime of Thomsons Lake was examined for the purpose of this analysis:

Rainfall data from the Bureau of (1952-1999)

Perth annual rainfall (1876 to 1985) (Cargeeg, et al., 1987, p.17)

Depth data (m AHD) from the Water Corporation (1952-1999)

Duration of dry periods (1962-1988) (Balla and Davis, 1993, p.38, Table 3.2)

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Rate of change per day (1974-1990) (Balla and Davis, 1993, p.41, Figure 3.1)

Bathymetry and vegetation distributions in relation to AHD (Arnold, 1990, p.270)

Frequency distribution of lake levels (Froend et al., 1993, p.20, Figure 3.6)

Groundwater abstraction volumes (1979-1985) (Cargeeg, et al., 1987, p.40)

Description of the water regime Seasonal drying occurred almost annually from the late 1970s to the late 1980s. Both prior to this period and during the 1990s drying did not occur as frequently (Figure 12). Due to the incomplete and highly variable nature of the depth data prior to 1971, it is difficult to draw firm conclusions about the nature of the historic water regime. The relatively high levels which characterised the lake’s water regime between 1964 to 1978 may have been a result of excessive inundation caused by clearing of the surrounding Banksia woodland for cattle grazing and market gardening (Crook and Evans, 1981).

Rapid changes in water level may have become more common since groundwater abstraction began in 1979, and the frequency at which rapid changes in depths occur may also have increased (Figure 13).

Vegetation Extensive mats of the aquatic macrophyte Myriophyllum sp. occur in the open water (ANCA, 1996). Above this a sedge community of Baumea articulata, Typha orientalis and Bolboschoenus caldwelli occurs. Typha orientalis became established during the 1980s and is considered to pose a threat by changing the community composition and the amount of open water (Directory of Important

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Wetlands web site). Above the level of T. orientalis, Baumea juncea occurs with a few shrubs, including Viminaria juncea and Acacia saligna. At higher elevation there is a woodland of Eucalyptus rudis, and Jacksonia furcellata (Halse et al., 1993) (Figure 14).

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1250

1000

750

500 Rainfall (mm)

250

0 1952 1954 1956 1958 1960 1962 1964 1966 1968 1970 1972 1974 1976 1978 1980 1982 1984 1986 1988 1990 1992 1994 1996 1998

16

15

14

13

12

Water level (mAHD)

11

10 1952 1954 1956 1958 1960 1962 1964 1966 1968 1970 1972 1974 1976 1978 1980 1982 1984 1986 1988 1990 1992 1994 1996 1998

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Figure 12. Hydrograph with rainfall data for Thomsons Lake, WA. Data provided by the Water Corporation and the Bureau of Meteorology. Note: The level of the lake bed is indicated on the hydrograph by a horizontal line. Data prior to 1971 were irregular and so do not show seasonal variation. From the mid-90s bores were not used for measurements, therefore after this time the level of the water table after the lake dries cannot be determined.

ENVIRONMENTAL WATER REQUIREMENTS FOR WETLANDS 103

4. FRAMEWORK

Figure 13 Rates of water level change at Thomsons Lake (from Balla and Davis, 1993, Figure 3.10, p.41)

Houses Eucalyptus

Elevation

m AHD Typha orientalis Typha Typha orientalis Typha Eucalyptus rudis Eucalyptus Eucalyptus rudis Eucalyptus Melaleuca sp.

18 Sedges, weeds, weeds, Sedges, Maximum weeds, Sedges, 16 15.5 mAHD 14 1968 12 10

Minimum 10.75 mAHD SCALE 1980 500 m

ENVIRONMENTAL WATER REQUIREMENTS FOR WETLANDS 105

Figure 14. Bathymetry, vegetation and water level records of Thomsons Lake (adapted from Arnold, 1990, Figure 9.16, p.270)

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Vegetation Extensive mats of the aquatic macrophyte Myriophyllum sp. occur in the open water (ANCA, 1996). Above this, but below the usual water mark, a sedge community of Baumea articulata, Typha orientalis and Bolboschoenus caldwelli occurs. Typha orientalis became established during the 1980s and is considered to pose a threat by changing the community composition and the amount of open water (Directory of Important Wetlands web site). Above the level of T. orientalis, Baumea juncea occurs with a few shrubs, including Viminaria juncea and Acacia saligna. At higher elevation there is a woodland of Eucalyptus rudis, Melaleuca preissiana and Jacksonia furcellata (Halse et al., 1993) (Figure 14).

Fauna Fourteen species of migratory waders occur at Thomsons Lake. The threatened Australasian ( poiciloptus), which is no longer recorded regularly at other , also occurs (Directory of Important Wetlands web site). Lists of waterbirds can be found at the Directory of Important Wetlands web site and in Crook and Evans (1981). Six species of wetland have been recorded: Crinia georgiana, Crinia insignifera, Heleioporus eyrei, Limnodynastes dorsalis, Litoria moorei and Litoria adelaidensis. The turtle Chelodina oblonga has been recorded at the lake. No fish have been recorded (Directory of Important Wetlands web site).

Ecological character The ecological character of Thomsons Lake was defined as

a shallow, seasonal to semi-permanent, groundwater-fed lake, with fringing sedge vegetation, which supports large numbers of waders in some years

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Step 2. Identify uses, values and threats

Uses Extraction of groundwater for domestic water supply for Perth occurs from the Jandakot Mound which also supports Thomsons Lake.

The lake is used for passive recreation such as walking and birdwatching (Directory of Important Wetlands web site).

Values Thomsons Lake is a Ramsar site and is of particular importance as a stop-over point for migratory waders. Both waterbird abundance and species diversity are high compared with other wetlands of the Swan Coastal Plain (Storey et al., 1993), and it is important locally as a refuge for the threatened (Botaurus poiciloptilus) (Directory of Important Wetlands web site). The importance of an appropriate water regime for waterbirds is both direct, as many have specific habitat needs in terms of water depth, and indirect, as the extensive sedge beds constitute important habitat for some waterbirds. The sedges themselves have particular water regime requirements.

Identified threats to the water regime of Thomsons Lake Threats to the lake’s water regime include both groundwater extraction and excessive inundation caused by clearing and urbanisation (Directory of Important Wetlands web site). The threat of excessive inundation mitigates the effect of groundwater extraction, however the overall effect has been estimated to be a reduction in the groundwater levels on the Jandakot Mound of between 0.10 and 1.10 m (Balla and Davis, 1993). In the future an expected increase in urbanisation on the Mound could possibly result in excessive inundation becoming a problem. Urban drainage may cause short-term water level fluctuations (see Figure 13). A proposal to drain land east of Thomsons Lake for housing development was subject to Environmental Protection Authority

ENVIRONMENTAL WATER REQUIREMENTS FOR WETLANDS 109

restrictions due to concern for the integrity of the lake’s water regime (EPA, 1990; Directory of Important Wetlands web site).

Wetland vegetation communities of the Swan Coastal Plain are considered to be dynamic, moving up- and down-gradient in response to increased or decreased inundation (Froend et al., 1993). However the shallow and essentially flat-bottomed nature of Thomsons Lake (Figure 14) means that a permanent reduction in groundwater levels would pose a threat to its ecological character. A relatively small reduction in groundwater levels would lead to a considerable reduction in the amount of open water.

Qualitative assessments of alterations to water budget elements are listed below (Table 4). Attempts to produce a quantitative water budget have been unsuccessful due to difficulties accessing adequate drainage data (Krasnostein, pers. comm.). As a result, the extent to which human impacts on the water regime mitigate against each other could not be determined. The overall direction of change in the water regime as a result of human activity (ie. groundwater abstraction vs land clearing) is therefore unclear.

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Table 4. Processes which may alter aspects of the water budget of Thomsons Lake.

Water budget Processes at Thomsons Lake which could alter elements Nature of alteration element of the water budget

P Climate change. Reduced Precipitation Rainfall has been below average since the early 1970s (Cargeeg et al., 1987)

Possibly increased from drain from south-east (which is Possibly increased Qi cleared, primarily agricultural land (ANCA, 1996)). Water Surface water from this drain enters the wetland after passing through constructed wetlands. These wetlands were constructed to inflow mitigate against increases in nutrient loads. The wetlands are bypassed at times of very high flow.

Reduced rainfall (above) may also result in a reduction of surface run-off

Could be reduced as a result of groundwater extraction Possibly reduced Gi Groundwater inflow

E May be affected by climate change and the extent/ health Possibly reduced Evaporation/ of vegetation transpiration

n/a Qo Surface water outflow

Dependent upon the level of the groundwater table Go Groundwater outflow

ENVIRONMENTAL WATER REQUIREMENTS FOR WETLANDS 111

Step 3. Determine management objectives

As a Ramsar wetland, a suitable general management objective is

To protect against decline in the ecological character of the site.

A specific management objective, based on the identified values, is

To protect the site’s habitat value for migratory waders.

The water regime of Thomsons Lake is currently managed by the Water Corporation to reduce the possible negative impacts of groundwater extraction and drainage of nearby areas for urban development. The existing management objective is

“to protect the ecological character of the lake and, in particular, its importance as a waterbird habitat” (EPA, 1990, p.4).

This objective addresses obligations associated with the Ramsar status of the site. Management is aimed at maintaining both the natural seasonality of the water regime, with lower water levels in summer, and the effect of annual rainfall variations on the lake water levels (EPA, 1990).

Step 4. Describe the relationships between water regime and wetland biota

Water requirements of wetland vegetation Table 5 lists general qualitative requirements of the wetland plant species of Thomsons Lake. These include adaptations to seasonal drying, and relatively shallow water for the submerged Myriophyllum sp.

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Table 5. General water regime requirements of vegetation

Type Species General Water Regime Requirements

Aquatic macrophyte Myriophyllum sp. Requires water that is not excessively deep (Balla and Davis 1993)

Emergent macrophyte Bolboschoenus caldwelli Requires seasonal drying: becomes established below sedges as the lake dries (Halse et al., 1993).

Trees (Eucalyptus rudis and Degraded by prolonged flooding (>2 years). Melaleuca preissiana) Where water levels fall over a long period of time, recruitment of young Melaleuca preissiana occurs at a lower elevation (Froend et al., 1993).

The water depth requirements of four emergent macrophyte species are listed below (Table 6). These species generally occur around the fringes of Thomsons Lake (Figure 14). A decrease in water levels such as occurred between 1979 and 1991 may lead to their encroachment towards the centre of the lake. Sedge vegetation in 1987 did in fact cover a greater area of Thomsons Lake than it did in 1963, which was a wetter year (Figure 12) (Froend et al., 1993, maps Appendix 1). In 1992, a wet year, water levels were very high, and the area occupied by sedges was much reduced in the following year as a consequence (Davis, pers. obs.). A long-term lowering in water levels would result in less open water habitat and an increase in sedge habitat. However large fluctuations in water levels between wet and dry years may be considered as part of the natural variability of the lake’s water regime. These fluctuations result in variability in the area of sedge habitat.

Table 6. Water depth requirements of emergent macrophytes

Species Range of Depths of Occurrence Mean Annual Depth (Froend et al., 1993) (Chambers et al., 1995)

Bolboschoenus caldwelli +0.3 to - 0.2 m

Baumea articulata Minimum - 1.0m +/- 0.4 m Maximum + 1.0m

Typha orientalis Minimum - 1.0m +0.1 m to - 0.3 m Maximum + 1.0m

ENVIRONMENTAL WATER REQUIREMENTS FOR WETLANDS 113

Baumea juncea +0.2 m to -0.3 m

Water Requirements of Wetland Fauna Vertebrates

Waders require shallow areas and the long-toed stint requires seasonally exposed mud flats. Therefore excessive inundation could potentially be a problem. The large areas of sedges and mud flats may` be critical as habitat for waders; maintaining a suitable water regime for the maintenance of these habitats should meet the requirements of waterbirds. Sudden increases in water level, due to urban drainage, and sudden decreases due to groundwater abstraction may adversely impact populations and aquatic invertebrates (Table 7).

When evaluating the habitat requirements of the vertebrates of Thomsons Lake, it is important to consider that the more mobile vertebrates may utilise the entire chain of the . As a whole, this group of wetlands provides a much higher variety of habitats than does Thomsons Lake alone (Crook and Evans, 1981). In particular, nearby Kogolup Lake has a permanent water regime and is used by waterbirds when Thomsons Lake dries up (Rod Smith, Birds Australia, pers. comm.). Mobile vertebrates include waterbirds and the turtle C. oblonga. C. oblonga can travel overland long distances, although in doing so many are killed on the roads (Bush et al., 1995). The predator-proof fence which now surrounds Thomsons Lake may prevent the movement of some non-flying fauna such as turtles.

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Table 7. Water regime requirements of wetland vertebrate fauna.

Type Species Water regime

Waterbirds Long-toed Stint Require exposed : only appear when these are present (Calidris subminuta) (Directory of Australian Wetlands web site)

Waders (general) Shallow water levels

* Australasian bittern Require tall sedges (Directory of Australian Wetlands web (Botaurus poiciloptilus) and site)* * Little bittern (Ixobrychus minutus)

Musk duck Require deep permanent water (Frith, 1957: Braithwaite and (Biziura lobata) Frith, 1968).

Blue-billed duck Require deep permanent water (Frith, 1957: Braithwaite and (Oxyura australis) Frith, 1968).

Frogs Limnodynastes dorsalia Survival of embryos within egg masses may require an and absence of sudden increases/ decreases in water levels, as the Litoria adelaidensis eggs are attached to vegetation and float on the water surface. The embryos may need to remain on the surface of the water to be both well-oxygenated and wet. Changes in depth which result in either the drying of the egg masses or their inundation (and subsequent de-oxygenation) may be detrimental (Seymour and Roberts, 1991; cited in Wilkins, 1993)

Heleioporus eyrei Water level increases between March and May may be detrimental to breeding success: this species lays eggs in burrows (Roberts and Main, 1993; cited in Wilkins, 1993).

Fish None present (ANCA, 1996)

Turtles Chelodina oblonga This species has two nesting periods (September-October and December-January) (Clay, 1981). May require the presence of water in December/January for the second nesting period, as turtles only eat when open water is present, aestivating when the wetlands dry during summer.

Other reptiles Insufficient data

Mammals Bandicoots Dense fringing vegetation (Species List: Crook and Evans, 1981) * * * See Table 6 for water regime requirements of Baumea articulata and Typha orientalis, the most abundant tall sedges.

ENVIRONMENTAL WATER REQUIREMENTS FOR WETLANDS 115

There appear to be few animal species which require permanent water for survival. Exceptions include the and the blue-billed duck. Musk ducks were recorded in each decade between 1954 to 1979 (Crook and Evans, 1981) but are not mentioned in the Directory (Directory of Important Wetlands web site). A loss of this species could be a result of the reduced water levels. The shift from the deeper, permanent water regime which characterised the lake prior to 1978, to the current shallower, seasonal or semi-permanent water regime may have resulted in a reduction in the abundance of diving ducks and an increase in the abundance of waders.

Invertebrates

Adult insects with aquatic larvae require healthy vegetation for resting sites. Some, including adult damselflies, require macrophytes for egg-laying sites. Therefore the maintenance of a water regime which will be suitable for macrophytes is of importance also for the maintenance of invertebrate habitat values. The aquatic invertebrate fauna of the Swan Coastal Plain wetlands are considered to be adapted to seasonal drying. The requirements of aquatic invertebrates should be met if seasonal wetlands do not dry out before December each year, and if rates of wetland drying do not exceed 0.02 m day-1 (Balla and Davis, 1993).

Nuisance Species

Increased depth may result in a shift from a system dominated by macrophytes to one dominated by phytoplankton (Balla and Davis, 1993). Cyanobacterial blooms may result, however cyanobacteria may be favoured by the mixing conditions which are typical of relatively shallow depths. Shallow lakes exposed to strong winds conditions (as Thomsons is) often experience diurnal or semi-diurnal cycles of complete mixing and secondary stratification, which favours cyanobacteria over other phytoplankton (Bailey and Hamilton, 1997). The phytoplankton of Thomsons Lake was found to be dominated by

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cyanobacteria between August and November, 1994 (Bailey and Hamilton, 1997) a time when the the lake was relatively deep (Figure 12).

A decrease in water levels may favour Typha orientalis while an increase in permanence could lead to the establishment of Gambusia holbrooki (Table 8).

Table 8. Nuisance/pest species that may be favoured by changes to the water regime.

Nuisance/pest Water regime changes favourable

Cyanobacterial blooms Excessive depth leading to the death of Myriophyllum sp. beds (Balla and Davis, 1993).

Typha orientalis Shallower regime

Introduced fish Gambusia Increased permanence holbrooki*

* Although not recorded at the lake this species colonises most wetlands with a permanent water regime on the Swan Coastal Plain and so there is a high possibility that it will occur in Thomsons Lake if the regime becomes permanent.

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Step 5. Determination of the desired water regime The water regime requirements of the biota of Thomsons Lake and bathymetry and hydrological data were used to develop a conceptual model (Step 6, Figure 11). This was developed to assist in the process of determining a suitable water regime.

Step 6. Refine the desired water regime using a conceptual model

Conceptual model

Scenario 1. Decreased water levels, seasonal water regime (Figure 15). An overall decrease in water levels would result in a shift of the fringing vegetation communities down-gradient (Froend et al., 1993). As the wetland has a relatively flat bed and steep sides, and the sedges and Typha occur where the land begins to rise out of the basin (Figure 14), reduction of water levels below a certain point could lead to a spread of the sedge and Typha vegetation across the bed of the lake. This would be associated with a loss of habitat for the aquatic Myriophyllum sp. (which supports a productive invertebrate fauna) and a loss of seasonally exposed mudflats, which are important for the long- toed stint, a migratory wader (Directory of Important Wetlands web site). Additionally, a reduction in water levels would be associated with recruitment of the wetland trees down-gradient of their present distributions. This is already occurring for Melaleuca preissiana at nearby Banganup Lake (Froend et al., 1993). If water levels decreased over time, sedges may take over the areas now characterised by open water and mud flats, leading to a loss of habitat for waders. With a further loss, E. rudis and Melaleuca sp. would take over the bottom of the basin.

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A long dry period SCENARIO 1. every year typically lasting Fringing trees December to July in poor health

Sedges invade the entire lake bed Typical annual water level range

Increasing water A dry period most but quantity SCENARIO 2. not all years, typically Fringing trees between February and June in good health

Sedge distribution varies Typical annual water level range between wet and dry years Optimum wader habitat in many years

Permanently inundated. SCENARIO 3. Rarely, if ever, experiences draw-down

Reduced sedge area Typical annual water level range

Diving ducks abundant

Figure 15. Conceptual modelling: scenarios describing wetland response to changing water regime (Thomsons Lake).

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Scenario 2. Seasonal or semi-permanent water regime: water levels intermediate between those of scenarios 1 and 3 (Figure 15). Wader habitat will be optimum if water levels are between approximately 11.5 and 12.5 m AHD (equivalent to depths between 0.3 m below the sediment and 0.7 m above) (Scenario 2, Figure 15). Higher water levels than this would result in a reduction of both wader habitat and the extent of sedge beds (Scenario 3, Figure 15); while lower overall water levels may result in an invasion of the entire lake bed by sedges (Scenario 1, Figure 15).

The long-toed stint (Calidris subminuta) occurs at Thomsons Lake when mudflats become exposed in summer/ autumn (Directory of Important Wetlands web site). This would occur only under scenario 2. This migratory species is protected by international agreements (Storey et al., 1993). The highest count, recorded in the summer of 1991, represented at least 1% of the probable national population of this species (Directory of Important Wetlands web site). This was a year when the lake dried (Townley et al., 1993). The required habitat of this species, exposed mudflats, only occurs seasonally in relatively dry years. Exposed mudflats would cease to occur if the water regime became permanent, or the wetland became excessively inundated.

Scenario 3. Deeper water levels, permanent water regime (Figure 15). An increase in water levels could lead to deaths of Myriophyllum sp. beds and possibly deaths of the lower E. rudis and Melaleuca sp., although these could re-colonise at a higher gradient (Arnold, 1990; Froend et al., 1993). A severe contraction of the sedge and Typha habitat could result (Figure 14). The most abundant waterbirds under this scenario are likely to be ducks and piscivorous birds. Waders would be less abundant, as would the threatened Australasian Bittern, which requires sedge habitat (Table 7). Diversity and abundance of invertebrates may be reduced by the reduction of macrophyte habitat and the

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establishment of conditions suitable for Gambusia holbrooki (Table 8). This may in turn reduce waterbird abundance. Deeper water levels may satisfy a possible alternative management objective of providing landscape amenity in the form of year-round open water views. However, if the increase in water level were to be associated with algal blooms as a result of a shift from a macrophyte-dominated system to a phytoplankton-dominated system, the amenity value would be reduced.

Scenario 4. Rapid water level fluctuations due to influence of drainage water. Rapid water level fluctuations may negatively impact the breeding success of the frogs Limnodynastes dorsalia and Litoria adelaidensis (details Table 7). Some aquatic insects may not be able to complete their life cycles before the lake dries. Waterbirds such as coots, with nests attached to vegetation may be negatively impacted by rapid changes in water levels.

Desired water regime The water regime of Scenario 2 satisfies the management objectives best. Inter- annual rainfall variation will mean that Scenarios 1 and 3 occur after successions of very wet or dry years. Scenario 4 may occur as a result of increased urbanisation.

Step 7. Performance indicators Performance indicators could be defined in terms of relative areas of various habitats. Inter-annual variation would have to be allowed for; for example, large-scale reduction in the area of Typha in wet years, and increases in dry years. This variability due to climate could be accommodated by wording the performance indicators in a similar manner to the water level criteria:

“The area of sedge vegetation is not to increase/decrease by more than a determined percentage for a certain number of years per decade, or for more than a certain number of consecutive years”.

ENVIRONMENTAL WATER REQUIREMENTS FOR WETLANDS 121

Additional performance indicators could be based on the breeding success of waterbird and frog species identified in the conceptual model as threatened by excessive water level fluctuations (Scenario 4).

Step 8. Determine the means of achieving the desired water regime The desired water regime could be achieved by setting environmental water requirements in terms of water levels, allowing for inter-annual variation due to climate variability. Human impacts such as groundwater extraction, urban development and drainage could be modified in order to meet these requirements. This has been the approach used in the management of Thomsons Lake’s water regime (WAWA, 1992).

Step 9. Set environmental water allocations to achieve the desired water regime Existing criteria were first examined to determine their sense not clear in this context.

Existing criteria for the management of the water regime of Thomsons Lake

WAWA’s operational criteria for the management of abstraction in terms of the water level of Thomsons Lake are:

“groundwater abstraction must not result in water levels falling between 10.8 and 11.3 m AHD more than once in any ten year period”

(WAWA, 1992, Section 3.5.3).

This criterion is compatible with scenario 2 of the conceptual model (Step 5).

Table 9. Relationship between criteria water levels in mAHD and water depths.

Water level in m AHD Approximate depth of water in the middle of the lake

10.8 1.0 m below sediment surface of the lake bed

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11.3 0.5 m below sediment surface of the lake bed

Water at the sediment surface of the lake bed. 11.8 Lake bed saturated but not inundated.

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Suitability of the water level criteria (WAWA, 1992) The minimum water level criteria for management is 10.8 m AHD (WAWA, 1992). This equates to the minimum level required for the health of emergent macrophytes. The point at which the water table is approximately at the surface of most of the lake bed occurs at 11.7 m AHD (Table 9) (Arnold 1990, p.269 Figure 9.15). When the water depth is at 10.8 m AHD, the water table is approximately 1.0 m below the ground level. According to Townley et al. (1993) this is the point at which the capillary rise of water can no longer reach the roots of emergent macrophytes (Table 10). Baumea articulata and Typha orientalis, the most abundant emergent macrophytes at Thomsons Lake, occur in the zone where the level of the water table varies between 1.0 m below and 1.0 m above ground level (Froend et al., 1993). The minimum water level criteria of WAWA (1992) should adequately protect the extensive sedge areas (Table 10). The other criteria, that the level not fall between 10.8 and 11.3 m AHD more than once every 10 years due to abstraction (WAWA, 1992), results in the water table not falling below 0.5 m of the sediment surface more than once every 10 years. This should also protect the health of the emergent vegetation, as the optimum water level for B. articulata and T. orientalis is + / - 0.1 m above the lake bed (Froend et al., 1993) (Table 10). This should in turn ensure the protection of fauna habitat, including waders and invertebrates.

Short-term water level fluctuations The issue of increased short term water level fluctuations is not covered by WAWA’s (1992) criterion. This has the potential to negatively impact invertebrate, frog and waterbird populations (Scenario 4, conceptual model). A maximum rate of change of 0.02 m.day-1 has been included as a criterion for wetlands of the Gnangara Mound (WAWA, 1995), on the basis of the requirements of aquatic invertebrate communities (Balla and Davis, 1993). This criterion could be incorporated into the general criteria for the management of Thomsons Lake.

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Table 10. Water regime criteria in relationship to depth and water regime requirements of wetland vegetation and fauna.

Criteria Effect of criteria in terms Match with water requirements of biota (WAWA, 1992) of the lake’s water regime. Water levels in m AHD

WAWA (1992): The water table should Townley et al., (1993): This is the point at which Groundwater abstraction never fall more than 1 m emergent macrophytes can no longer access water. must never result in water below the lake surface*. levels falling below 10.8 m Matches the lowest water level that Baumea AHD. (Water levels are articulata and Typha orientalis can survive. artificially maintained to meet this criteria).

WAWA (1992) The water table should not Preserves the health of sedge beds, and therefore Groundwater abstraction fall in the range of 0.5 to their extent. must not result in water 1.0m below the surface of levels falling between 10.8 the lake bed more than once and 11.3 m AHD more than every 10 years**. once every 10 years.

WAWA (1992) Preserves seasonal drying Seasonal drying is linked to increased productivity Minimum water level not in 9 out of 10 years. of aquatic invertebrates, which should result in exceed 11.8 m AHD more large numbers of waterbirds (Crome, 1988). than once every 10 years. The preservation of the natural variability of the water regime may be important in the maintenance of fringing vegetation (Brock and Casanova, 1997).

Preservation of the natural seasonality is likely to be critical for the health of the fringing trees, which include Eucalyptus rudis and Melaleuca preissiana (Froend et al., 1993).

Seasonal drying allows for the exposure of mudflats in summer/autumn, which is required by the Long-Toed Stint (a migratory wader) (Directory of Important Wetlands web site).

Seasonal drying should reduce the potential for Gambusia holbrooki to colonise and achieve high densities, and result in an aquatic invertebrate community typical of seasonal wetlands.

*With an annual difference between maximum and minimum water levels of 1.5 m (from hydrograph in Townley et al., 1993 Figure 4.1.7 p89), the maximum water level attained annually should not fall below 1.0m. ** With an annual difference between maximum and minimum water levels of approximately 1.5 m, the maximum water level attained annually should not fall below 0.5 to 1.0m more than once every 10 years.

Steps 10 and 11. Implementation and Monitoring Biological monitoring regimes should be designed to test performance indicators related to the area of sedge habitat and waterbird and frog breeding

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success. Biological monitoring should also incorporate an invertebrate monitoring program. Hydrological monitoring should include daily depth measurements to indicate rates of change of depth as well as actual depths.

Conclusion A lack of historical hydrological data for Thomsons Lake means that the management of the water regime cannot be based on an attempt to reinstate the regime which existed prior to development. WAWA’s (1992) management objective, based on the maintenance of ecological character and the protection of waterbird habitat, reflects the ecological values and Ramsar status of the site. The methodology allowed a suitable water regime to be determined based on the requirements of the desired and/or existing wetland flora or fauna.

WAWA’s (1992) criteria appear to meet the water regime requirements of the sedge habitat whilst also maintaining suitable water levels and a seasonal/ semi-permanent water regime to meet the requirements of waders. They do not address the threat of increased short-term water level fluctuations. Additional criteria addressing this issue should be incorporated into the current criteria. A monitoring program should ideally incorporate daily water level monitoring and a biotic monitoring program focussed on performance indicators. These should be based on the identified changes to flora and fauna communities identified in the conceptual model.

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Bool Lagoon

Step 1. Characterise the wetland

Hydrology Location and Bathymetry

Bool Lagoon lies in the south-east of South Australia, and comprises thee interlinked basins (Figure 16).

Figure 16. Bool Lagoon (from Brownlow et al., 1994, p.1376). Inflow occurs via Mosquito Creek, and outflow occurs via the outflow channel.

Water regime

The water regime is artificially manipulated as the wetland is used as an equalisation basin for flood mitigation. It now acts as a sump for a catchment of 1215 km2. In the past it was filled from the overflow from Mosquito Creek during winter, but most of the creek flows bypassed the lagoon. The water regime is more permanent now than it was in the past. Most of the wetland now dries out approximately once every two years (ANCA, 1996). It could

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therefore be characterised as semi-permanent. There is a gradient of permanency within the wetland; Hacks Lagoon is the deepest and generally contains water all year round, with a depth range of 0.3-1.40 m (Brownlow et al., 1994).

Source

Bool Lagoon receives water also naturally as part of a regional drainage scheme. Water tables in the area are rising (ANCA, 1996). In terms of a water budget, surface water flowing in to the wetland has increased and groundwater flowing in may have increased as a result of the rising water table.

Depth

Average depth is 1 m, and the maximum recorded is 1.5 m (ANCA, 1996). The mean maximum depth is 0.94 to 1.09 m (Denton and Ganf, 1994).

Existing management of the water regime

Water levels are now managed for a draw down period when necessary for the benefit of vegetation (ANCA, 1996).

Ecology Flora

Threatened species include Baumea rubiginosa and Rumex bidens (ANCA, 1996). Dominant vegetation is shown in Table 11.

Table 11. Dominant flora of various zones of Bool Lagoon (ANCA, 1996).

Zone Dominant species

Main basin Triglochin procera

Lagoon edge reedbeds Phragmites australis Typha domingensis

Lagoon edge rushbeds Baumea articulata Baumea juncea

Tussock sedgeland Gahnia filum Gahnia trifida

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Wet herblands on mudflats around lagoon margins Schoenus nitens

Grassland Distichlis distichophylla Sporobolus virginicus

Tussock grassland Poa labillardieri Gahnia filum

Woodlands in the south east corner of the main basin Melaleuca halmaturorum

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Fauna

The Directory lists seventeen threatened species of waterbird and fourteen species of migratory waders. Other fauna include frogs, native and introduced fish, the eastern snake-necked tortoise (Chelodina longicollis) and the water rat (Hydromys chrysogaster) (ANCA, 1996).

Ecological character Bool Lagoon is a semi-permanent wetland with a diverse riparian flora, including a stand of Melaleuca halmaturorum, which provides important habitat for waterbirds.

Step 2. Identify uses, values and threats

Uses is usually opened for duck hunting for several mornings per year, dependent upon conditions (Directory of Important Wetlands web site).

Values Bool Lagoon is listed as a Ramsar site (Directory of Important Wetlands web site; Ramsar site 322). The wetland is of importance for waterbirds and of national importance for colonial nesting birds (ANCA, 1996). It is an important drought refuge for waterbirds, and provides breeding habitat for waterbirds (Directory of Important Wetlands web site). Much of the surrounding area has been drained for agricultural purposes.

Threats Recruitment of M. halmaturorum has been negatively affected by the increased permanence of the water regime (Denton and Ganf, 1994).

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Step 3. Determine management objectives

General

To protect against decline in the ecological character of the site.

Specific

1. To protect the site’s habitat value for migratory waders and rare and endangered waterbirds.

2. To preserve the existing vegetation distributions.

The general objective relates to the site’s Ramsar listing. The specific objectives relate to the identified value of the site for waterbirds, and the identified threat to the Melaleuca woodland, respectively.

Step 4. Describe relationships between biota and water regime

Flora The health of Melaleuca halmaturorum juveniles is negatively impacted where floods exceed six to nine weeks. The dominant stand at Bool Lagoon was found to be restricted to mature individuals. Germination was observed to occur, but seedlings failed to become established. An experiment confirmed that juvenile trees were adversely affected by flooding (Denton and Ganf, 1994). The lack of juveniles in the stand of M. halmaturorum therefore appear to be a result of the increased depth and permanence of the water regime. This is a long-lived species, with a lifespan of more than 100 years (Denton and Ganf, 1994). The increased permanence of the water regime appears to have negatively affected Baumea arthrophylla and positively affected Triglochin procerum (Table 12).

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Table 12. Water regime requirements of wetland plants of Bool Lagoon, and effects of the altered water regime.

Species Type Water regime requirements Affect of altered water regime

Melaleuca halmaturorum Tree Juveniles cannot tolerate Recruitment no longer occurs inundation of more than 6 to 9 weeks (Denton and Ganf, 1994)

Baumea arthrophylla Emergent Suited to seasonally fluctuating Became less abundant: now only aquatic water levels (Rea and Ganf, occurs in the south-west of the 1994) wetland (Rea, 1992 cited in Denton and Ganf, 1994)

Triglochin procerum Semi- Invaded deeper areas (Rea, 1992, emergent cited in Denton and Ganf, 1994) aquatic

Fish The eggs of western carp gudgeon (Hypseleotris klunzingeri) are vulnerable to desiccation, as are those of the dwarf galaxias (Galaxias pusilla). However, juveniles and adults of the dwarf galaxias (Galaxias pusilla) can survive in swamps which may be dry for up to 5 months (Beck, 1985, cited in Koehn and O'Connor, 1990).

Frogs The frog Limnodynastes peronii occurs at Bool Lagoon and is considered to require permanent water (Cogger, 1996).

Mammals The abundance of water rats may be favoured by permanent inundation (Scott and Grant, 1997). Breeding occurs in spring and summer; flooding during this time may result in some mortality of young but this effect may be offset by the increased food availability.

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Waterbirds Waterbirds which inhabit and breed in Bool Lagoon have specific water regime requirements (Table 13), and will therefore be affected by water regime management. Complete drying on an annual basis may negatively affect breeding of intermediate egrets and little black cormorants (Crome, 1988, Table 13), while if the annual dry phase regularly lasts more than two months great egrets breeding will be negatively impacted (Briggs et al., 1994, cited in Scott, 1997, Table 13). Complete drying will negatively impact musk ducks and blue-billed ducks (Table 13, Frith, 1957). However, for other ducks, complete drying of the wetlands is likely to result in large breeding events in subsequent floods (Crome, 1988, Table 13). The movements and breeding of many ducks (such as pink-eared ducks) are strongly influenced by weather. These species travel large distances to exploit wetlands with suitable conditions (Frith, 1957).

Table 13. Water regime requirements of waterbirds.

Species/ Group Requirements

Great egret (Egretta alba) Breeding requirement: minimum duration of flooding is 10 months (Briggs et al., 1994, cited in Scott, 1997)).

Intermediate egret (Egretta intermedia) and At Booligal, NSW, were found to breed best when the swamps had been filled for a long time. These species are Little black cormorant (Phalacrocorax sulcirostris) fish-eaters (Crome, 1988)

Ducks (general) Breed in large numbers in floods after complete drying out of swamps (Crome, 1988).

Musk duck (Biziura lobata) Require permanent deep water (Frith, 1957). Favoured by the stable conditions found in irrigation drainage swamps. Blue-billed duck (Oxyura australis)

Grey teal (Anas gibberifrons) Prefers rising water levels (Frith, 1957)

Pink-eared duck (Malacorhynchus membranaceus) For breeding requires residual flood waters which are drying up. Movements and breeding are dominated by weather

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(Frith, 1957).

Waterbird use of wetland trees The stands of M. halmaturorum at Bool Lagoon are important for ibis (LWRRDC, 1997) and may also affect the habitat value of the wetlands for maned ducks and spoonbill (Table 14). The survival of the stand of M. halmaturorum may be important for waterbird habitat values.

Table 14. Waterbird use of trees.

Waterbird Tree use

Ibis Nest in the old stands of Melaleucas at Bool Lagoon (LWRRDC, 1997b)

Spoonbills Sometimes nest in outer branches of large trees (Simpson and Day, 1993)

Maned duck (Chenonetta jubata) Often perch in trees (Simpson and Day, 1993)

Step 5. Determine the desired water regime to fulfil management objectives

The alteration of the water regime from seasonal to permanent which occurred with irrigation development appears to have resulted in ecological change, the most obvious being the lack of recruitment of M. halmaturorum. The existing fauna includes species adapted to seasonal water regimes, as well as species which require permanent water. Some of the species requiring permanent water, such as musk ducks and blue-billed ducks, are typical of irrigation drainage swamps (Frith, 1957).

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The desired managed water regime would include periodic draw-down to allow the recruitment of M. halmaturorum. Denton and Ganf (1994) suggest that draw-downs for this purpose need only occur approximately once every 10 years. This would satisfy the second specific management objective, regarding the preservation of existing vegetation distributions. Draw-downs would benefit duck breeding. The breeding of great egrets would be protected by including periods of inundation greater than 10 months, achieved either by draw-down occuring less frequently than annually, annual draw-down of brief duration, or draw-downs not resulting in the drying of the deeper Hacks Lagoon. The retention of water in Hacks Lagoon would retain the value of the wetland as a drought refuge for waterbirds and would allow the survival of any wetland fauna which require permanent water. This would satisfy the first specific management objective regarding the habitat value of the wetland for waterbirds. The general management objective would be also be satisfied, as the ecological character of the site has been defined as a “semi-permanent wetland, with diverse riparian flora, including a stand of M. halmaturorum, which provides important habitat for waterbirds.”

Step 6. Refine the desired water regime by examining various scenarios using conceptual modelling

Scenario 1: Permanent water regime Under this scenario, natural recruitment of M. halmaturorum would not occur except at the higher elevations (Denton and Ganf, 1994). The reduced area of M. halmaturorum woodland would directly negatively impact ibis populations (LWRRDC, 1997b) and possibly also other waterbird species (Table 14). One alternative is the mass planting of established saplings of M. halmaturorum (Denton and Ganf, 1994). Disadvantages of this alternative include the cost and the possible continued adverse effects on other species. While the adverse effects of the altered water regime on this long-lived tree species have been

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identified, effects of the altered water regime on other species may not be as obvious.

The resultant very stable water regime is likely to be associated with reduced duck breeding (Table 13, Crome, 1988).

Scenario 2: Managed draw-downs most years, with complete drying of the wetland If draw-down occurred in most years, natural recruitment of M. halmaturorum could occur more frequently. The area occupied by Triglochin procerum would be reduced, possibly to be replaced by Baumea arthrophylla. The value of the wetland as a drought refuge to waterbirds would be reduced or lost if complete drying was to occur frequently. This is a concern as wetlands in much of the surrounding area have been lost (Step 2, Values). Some fauna which may have benefited by the increased permanency of the water regime (eg musk duck, blue-billed duck, some species of frogs and fish) while others may be lost. Abundance of fish-eating waterbirds such as the intermediate egret and the little black cormorant would be reduced. If the hydroperiod was generally less than 10 months, breeding of the great egret may be negatively affected.

Scenario 3: Occasional managed draw-downs characterised by incomplete drying (water to be retained in Hacks Lagoon). Denton and Ganf (1994) argue that species diversity may best be preserved by a managed water regime that is “adaptable” rather than “fixed”, that is, a water regime that incorporates inter-annual variability. They suggest that water levels be manipulated approximately once every 10 years to allow the occasional recruitment of M. halmaturorum. In the summer of 1993-4, low water levels were achieved by manipulating the regulator gates, to facilitate M. halmaturorum recruitment (Denton and Ganf, 1994). This would have few negative impacts on other species; fish and frogs requiring permanent water could survive in Hacks Lagoon. Large duck breeding events could occur after the infrequent managed draw-down.

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Refined desired water regime Scenario 3 (described above) may best preserve the identified values of this wetland, in particular waterbird habitat values associated with its Ramsar status.

Step 7. Set performance indicators Performance indicators could be based on successful M. halmaturorum recruitment, waterbird breeding, and waterbird abundance and species present.

Step 8. Determine the means of achieving the desired water regime Regulator gates at the outlet allow manipulation of the water regime (Denton and Ganf, 1994).

Step 9. Prescribe environmental water allocations to achieve the desired water regime Environmental water allocations could be set based on occasional manipulation of the water level (approximately once every 10 years) to achieve summer levels low enough to allow recruitment of M. halmaturorum. Flexibility could be incorporated into the allocations, based on climate variability and the health of previous cohorts of M. halmaturorum juveniles. The allocations should also deal with a possible change towards greater permanency and increased depth which may result from the rising water table. If this occurs greater intervention may be required.

Steps 10 and 11. Implementation and Monitoring Hydrological monitoring should be based on frequent depth measurements. More detailed hydrological measurements would allow a water balance to be calculated, and the risk posed by rising water tables could be assessed. Biological monitoring should include monitoring of the health of M. halmaturorum juveniles, waterbird use, waterbird breeding, and the presence of other fauna such as frogs, tortoises and water rats.

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Lower Gwydir Wetlands Step 1. Characterise the wetland

Hydrology The Lower Gwydir wetlands are semi-permanent terminal wetlands of the Gwydir River (Keyte, 1994). They comprise floodplain wetlands of two major streams of the Gwydir River, the Gingham Watercourse and the Lower Gwydir Watercourse. The hydrology of the wetlands has been altered by the Copeton Dam, weirs, and regulators which divert water for irrigation, stock and domestic use (Keyte, 1994).

Ecology Vegetation

McCosker and Duggin (1993) have defined the wetland in terms of management units. The hydrology and vegetation communities of the units most affected by alterations to hydrology are indicated in Table 15.

Table 15. Vegetation communities at the Gingham Watercourse most threatened by altered water regime (McCosker and Duggin, 1993).

Unit Hydrology Vegetation communities

Low floodplain Flooding frequency less Open coolabah woodlands (Eucalyptus coolibah) with an understorey than that of the of river cooba (Acacia stenophylla) and lignum (Muehlenbeckia Watercourse Unit florulenta)

Watercourse Prior to the completion of Dominant vegetation is water couch (Paspalum distichum) and ribbed the Copeton Dam, subject spike rush (Eleocharis plana) meadows. to regular inundation Stands of dead coolabah trees River cooba and lignum

Fauna

These wetlands provide an important resource for waterbirds on a regional scale as their flooding is not always synchronous with flooding of other

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Murray Darling Basin wetlands such as the Macquarie Marshes or the Narran Lakes (Directory of Important Wetlands web site). The wetlands are significant for the large numbers of breeding waterbirds that have been recorded (Ramsar web site). Abundance, species diversity and breeding of waterbirds have declined. The abundance of colonial nesting birds (cormorants, herons and egrets) is reported to have declined, as has the abundance of waterfowl, large rails and (Debus, 1989, cited in Keyte, 1994). This has been at least partly attributed to the reduced quantity of water entering the wetlands (Keyte, 1994). A successful large breeding event occurred in the summer of 1999, however after the introduction of new water sharing rules (Nickson, 1999). There is anecdotal evidence that abundance of water rats, frogs and red-bellied black snakes has declined (Keyte, 1994).

Ecological character The wetlands are of a terminal riverine wetland type, ecologically significant for their large area of water couch and ribbed spike rush meadows, and their habitat value for waterbirds.

Step 2. Identify uses, values and threats

Uses Two major land uses that affect the wetland are grazing and irrigation for cotton-growing (Directory of Important Wetlands web site). Grazing occurs in the Ramsar site and in wetland outside the Ramsar site, and relies on flooding for the promotion of pasture growth. This is adversely affected by river regulation and the transfer of unregulated flows for irrigation (McCosker, 1994). Some of the wetland area outside the Ramsar site has been cleared for cereal cropping and cotton-growing.

Values Ecological

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Ecological values of the wetlands include their habitat value for waterbirds and the large area of water couch (Paspalum distichum) and marsh club-rush (Bolboschoenus fluviatilis).

Economic

The wetlands are situated on very productive grazing land, and represent a drought refuge for stock (Keyte, 1994).

Threats The over-riding threats to the wetlands is a reduction in the frequency and magnitude of flooding, resulting in a reduction of the quantity of water reaching the wetlands. There has been a 70% reduction in the occurrence of flows large enough to flood the Gingham and Lower Gwydir watercourse wetlands. The consequences include a serious and continuing contraction of reed beds, and weed invasion into water-couch and spike rush meadows (Table 16, Keyte, 1994).

Table 16. Nature of alteration to water regime and effect on vegetation at the Gingham Watercourse (McCosker and Duggin, 1993).

Unit Alteration to Affect of altered hydrology on vegetation hydrology

Low floodplain Reduction in medium Invasion of lippia (Phyla canescens) and moderate floods River cooba and lignum under stress as a result of insufficient flooding. since river regulation

Watercourse Reduction in the Spread of lippia, especially on land subject to irregular and short frequency and duration duration flooding. of flooding. Contraction of water couch and ribbed spike rush meadows during the last 10 years as a result of a reduction in the frequency and duration of flooding. Dead coolabah trees. The deaths have been attributed to prolonged inundation during the 1950s floods.

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Step 3. Determine management objectives General

To protect against further decline in the ecological character of the site.

Specific

1. To protect the site’s habitat value for waterbirds, with particular reference to the amount of waterbird breeding.

2. To reduce the area of weeds such as lippia.

3. To maintain the health of native vegetation.

4. To maintain current vegetation distributions, or where possible, reverse the incursion of terrestrial vegetation into core wetland areas which has occurred since the completion of the Copeton Dam.

Step 4. Describe relationships between biota and water regime The reduction in the frequency of small to medium floods (as a result of diversion for irrigation) is considered responsible for the displacement of aquatic and semi-aquatic vegetation with terrestrial vegetation, and the invasion of weeds including lippia (Phyla canescens). These effects may be accelerated by grazing (Bacon et al., 1992, cited in Keyte, 1994).

Estimates of the water requirements of the dominant plant species have been made (Keyte, 1994, shown in Table 17). These are based on the estimated water regime that occurred in each wetland community before river regulation.

Table 17. Estimates of flood frequencies required by dominant plant species (Keyte, 1994, using data from Craig et al., 1991 and Rankine and Hill, 1979).

Wetland type Dominant species Flood frequency Flood duration Type of flood event estimates estimate

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Core wetland Bolboschoenus once per year 30-180 days Freshes, minor fluviatilis floods Watercourse Water couch and 1 in 1-2 years 30-180 days Minor/moderate ribbed spike rush floods meadows. Intermittent wetlands River cooba/ lignum 1 in 3-7 years 30-120 days Moderate/major floods Floodplain Coolabah 1 in 10-20 years less than 30 days Major floods

Fauna Maintenance of the health of lignum and river cooba is important for the long- term maintenance of waterbird populations (Keyte, 1994). Water birds may require longer inundation periods for breeding than the periods required for vegetation health. Briggs and Thornton (1988) suggest minimum inundation periods of 5-10 months for the management of river red gum wetland water regimes for waterbird breeding. This allows species such as darters, cormorants, herons, egrets, spoonbills and to breed. These species require relatively long inundation periods, while ducks are able to breed successfully with shorter inundation periods. Minimum inundation periods of 5 to 10 months, therefore, allow the breeding of a large number of waterbird species.

Step 5. Determine the target water regime The desired water regime for each wetland vegetation type is indicated by the estimated water requirements of the dominant plant species (Table 17). Longer durations than those required by plants may enhance waterbird breeding; these may be achieved in high rainfall years rather than every year.

Minimum flooding requirements have been calculated to meet the plant water requirements of the Gingham Watercourse wetlands (McCosker and Duggin, 1993). Volumes of water have been determined to deliver flow events in the categories of freshes, minor floods, moderate floods and major floods for

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various wetland vegetation types (core wetland, water couch, river cooba and coolabah, respectively).

Step 6. Refine the desired water regime by examining various scenarios using conceptual models

Scenario 1: Current situation.

Scenario 2: Meeting vegetation requirements; increased frequency of inundation, minimum duration.

healthy native vegetation,

limited waterbird breeding except in unusually wet years

Scenario 3: Longer duration of inundation.

healthy vegetation,

large waterbird breeding events.

Step 7. Set performance indicators in relation to biota Performance indicators should relate to:

waterbird breeding events

waterbird abundance

waterbird species diversity

weed abundance

vegetation health with specific reference to trees (due to their habitat value for birds)

area of water couch and spike rush meadows

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Step 8. Determine the means of achieving the desired water regime Estimates of water volumes required to achieve and maintain inundation have been made using a water budget, for both wet and dry antecedent conditions (McCosker and Duggin, 1993). The means of achieving the desired water regime would involve the resolution of trade-offs with other water users, due to the over-allocation of water for consumptive uses.

Step 9. Prescribe environmental water allocations to achieve the desired water regime Environmental water allocations would need to incorporate the natural seasonality and variability of inundation.

Steps 10 and 11. Implementation and Monitoring

Water depth monitoring programs would be designed to measure the frequency and timing of inundation, Depth measurements would need to be taken within each wetland vegetation community. Biological monitoring programs would be designed to measure the performance indicators.

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Boggomoss Springs Step 1. Characterise the wetland

Site Description The site is located 20 km north-east of Taroom and lies within the Fitzroy catchment in Queensland, in the Brigalow Belt South bioregion. It consists of artesian springs scattered over an area of approximately 400 ha (Directory of Important Wetlands web site).

Hydrology The springs arise from the Great Artesian Basin and flow permanently. There is variation in flow, some of which is related to seasonal factors (Directory of Important Wetlands web site). The water depth of the wetland is 0.05-0.1 m.

Ecology General

The permanently saturated nature of the springs provides a habitat markedly different from that of the surrounding region. The flora also differs from that of other artesian springs (Directory of Important Wetlands web site).

Vegetation

The plant community of the springs is rare (Directory of Important Wetlands web site), and there are species of uncertain taxonomic status.

Fauna

An undescribed snail species occurs in the springs (Directory of Important Wetlands web site).

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Ecological character Permanent springs fed by artesian water, with little-known wetland animal and plant species, many of which are likely to be dependent upon the permanent flow of water to the springs for their survival.

Step 2. Identify uses, values and threats

Uses Landuses of the area include grazing and broadacre farming. The springs are an important water source for livestock (Directory of Important Wetlands web site).

Values Ecological

The Boggomoss Springs are a good example of active artesian springs, a rare habitat (Directory of Important Wetlands web site).

Cultural

Artesian springs generally have significant Aboriginal cultural value (Reyenga et al., 1998).

Economic

Economic values of the site are associated with grazing and agriculture, while the artesian water is of value for stock and domestic use (Directory of Important Wetlands web site).

Threats Aquifer drawdown through high usage of artesian water in the Great Artesian Basin.

The proposed Nathan Dam could result in the flooding of some of the springs.

(Directory of Important Wetlands web site).

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Step 3. Determine management objectives General

To protect against decline in the ecological character of the site.

Specific

To protect against decline in flow.

(This could be considered a general management objective for all artesian springs of the Great Artesian Basin).

To protect the Boggomoss Springs from hydrological alterations associated with the Nathan Dam.

Step 4. Describe relationships between biota and water regime Where little information exists concerning the water regime requirements of flora and fauna of artesian springs, it could be assumed that at least some species require permanent water, as the water regime of the springs has been permanent. As many artesian spring species are endemic (Reyenga et al., 1998), the reduction of habitat associated with any decline in flow could conceivably endanger endemic populations. The water regimes of some of the springs are also threatened by flooding by the proposed Nathan Dam (Directory of Important Wetlands web site). If the springs were flooded in this way the hydrology and hence water quality and quantity would be completely altered.

Step 5. Determine the desired water regime The desired water regime would be characterised by:

no loss of aquifer pressure, and

no flooding of springs associated with the proposed Nathan Dam.

ENVIRONMENTAL WATER REQUIREMENTS FOR WETLANDS 149

Step 6. Refine the desired water regime by examining various scenarios using conceptual modelling

Ecological effects of the following scenarios could be explored:

Scenario 1: Maintenance of present aquifer pressure and spring flows. No flooding associated with the Nathan Dam.

Scenario 2: Reduced aquifer pressure leading to the extinction of some of the springs.

Scenario 3: Reduction in aquifer pressure leading to the complete extinction of the springs.

Scenario 4: Flooding of some of the springs by the proposed Nathan Dam.

Step 7. Set performance indicators in relation to biota Performance indicators for Boggomoss Springs, and for artesian springs generally, could perhaps be related to population sizes of wetland flora and fauna.

Step 8. Determine the means of achieving the desired water regime The Great Artesian Bore Rehabilitation Project is a joint Federal and State Government Initiative aimed at the reduction of water wastage (Queensland Department of Natural Resources web site). A reduction of approximately 140 megalitres a day has been achieved through the installation of control valves and the use of piping rather than open drains. Bore rehabilitation efforts could be focussed more on the area where recharge occurs for the springs.

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Step 9. Prescribe environmental water allocations to achieve the desired water regime In the case of artesian springs, initiatives such as the Great Artesian Basin Rehabilitation Project may be adequate to control aquifer drawdown. This solution differs from the allocations of other types of wetlands in that it is large-scale rather than being aimed at individual wetlands

Steps 10 and 11. Implementation and Monitoring Hydrological monitoring

Monitoring of aquifer pressure and flow at the Springs would indicate whether the large-scale management strategy of the Great Artesian Basin Rehabilitation Project is adequate.

Biological monitoring

Monitoring should be aimed at the estimation of the population sizes of artesian spring species.

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5. OPPORTUNITIES AND LIMITATIONS

Introduction Limitations and opportunities for implementing environmental water allocations vary according to the nature and degree of human impact on the water regime, and the source of the water. They are therefore discussed in terms of broad groups of wetlands. Further details are shown in Table 18. The presence of physical structures such as dams, weirs, irrigation channels and levee banks may limit the ability to deliver environmental water allocations. Other limitations are related to the relatively large-scale problems such as rising water tables and the consumptive demand for water. The ability to determine appropriate water allocations is frequently limited by knowledge regarding both the pre-development water regime and the requirements of biota. Significant opportunities for environmental water allocations exist where abstraction occurs and is characterised by a large amount of wastage (eg unregulated artesian bores), and in isolated wetlands where water regimes may be manipulated relatively easily. These limitations and opportunities are explored in more detail below for groups of wetlands.

Riverine wetlands affected by excessive water extraction Water regimes of many riverine wetlands (both terminal and floodplain) of the Murray-Darling Basin are severely affected by upstream abstraction of water. Examples include the Lower Gwydir wetlands, Narran Lakes, the Great Cumbung Swamp, the Macquarie Marshes and the Barmah Forest. Limitations to the provision of environmental water for these wetlands include the demand for water for consumptive purposes, and over-allocation of water for consumptive purposes. The delivery of large floods is limited by legal liability. In addition, the presence of dams and other regulatory structures such as levee banks restricts the ability to return these wetlands to the pre-development water regime. There is also often a lack of data regarding pre-development water

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regimes. For these reasons it has been argued that rehabilitation may represent a more achievable management goal for these wetlands than the restoration of the historic water regime (Roberts et al., 2000). A certain level of change in wetland biota may be inevitable.

The Narran Lakes in are adversely affected by upstream abstraction in Queensland. This is an example of a potential political limitation of the management of wetland environmental water allocations.

While environmental water allocations for these riverine wetlands may be associated with an economic cost to irrigators (due to a reduction in water allocated to consumptive uses), they are likely to be associated with economic benefits to graziers. This is because the increased flooding frequencies resulting from environmental water allocations benefit floodplain pastures. Excessive extraction for irrigation negatively affects grazing values as well as conservation values. Areas of agreement and conflict between the views of graziers and irrigators have been examined in terms of management of water resources of Macquarie Marshes (Brock, P., 1996). Interestingly, it was found that despite differences there was consensus that the Marshes should be maintained in at least their present (1996) condition.

A review of the social and economic costs and benefits of irrigation can be found in Morrison (1999).

Barmah-Millewa Forest Large dam releases are considered to be an environmentally suitable solution for the Barmah-Millewa Forest, but the associated socio-economic costs of this are considered too high (Leitch, 1989). Water management is therefore carried out with the use of engineering structures to efficiently deliver water to where

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it is needed (Barmah-Millewa Forum and MDBC, 2000). Management difficulties associated with the location of the forest in two states is addressed by the existence of the Murray-Darling Basin Commission. The negotiation of trade-offs between various stakeholders is likely to be made easier by the creation of the Barmah-Millewa Forum.

Riverine wetlands threatened by increased permanence due to irrigation drainage water and/or river regulation There are often opportunities to manipulate the water regimes of individual small or isolated wetlands made permanent as a result of irrigation drainage water or river regulation. Seasonal drying can be restored through the use of flow regulators, with environmental benefits and minimal costs. Examples include Bool and Hacks Lagoon (irrigation drainage) and Lake Woolpolool on the Chowilla floodplain (river regulation). (Details are included in the Literature Review, Section 2).

Great Artesian Basin (artesian springs) Aquifer drawdown in the Great Artesian Basin threatens both conservation values and the consumptive use of water, as it causes the reduction or cessation of flow from bores as well as springs (Reyenga et al., 1998, Qld Department of Natural Resources web site). Efforts to reduce wastage therefore have social and economic benefits in addition to environmental benefits. There may be scope to target springs which are of particular importance due to their endemic fauna. Efforts to reduce wastage could be focussed on the recharge areas of these springs in an effort to avoid the extinction of their flow.

Wetlands impacted by alterations to drainage associated with agriculture The effect of drainage of wetlands for agricultural development in Queensland’s Wet Tropics is the direct loss of wetlands. Other threats to wetland water regimes as a result of agriculture include altered wetland

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hydrology due to drainage from adjacent agricultural land (Tasmania) and the deliberate drainage of a wetland in an attempt to improve the drainage of nearby pasture (Logan Lagoon, Tasmania) (Directory of Important Wetlands web site). In the case of these wetlands there appears to be a direct conflict between agricultural and pastoral landuse and conservation values associated with wetlands.

Cape Range subterranean wetlands, Western Australia Flow in these wetlands may be threatened by groundwater extraction for town water supply (Hamilton-Smith et al., 1998, Directory of Important Wetlands web site). Expansion of the township and of tourism may lead to an increase in water use which may threaten flow to these wetlands.

Wetlands of the Western Australian wheatbelt threatened by excessive inundation (eg Lake Toolibin) Wetlands of the Western Australian wheatbelt are threatened by excessive inundation caused by rising water tables resulting from the clearing of deep- rooted perennial native vegetation. Associated problems are salinity and water- logging. Both salinity and excessive inundation negatively impact wetland flora and fauna. Limitations to the ability to reduce excessive inundation of wetlands of these wetlands are generally associated with the very large-scale nature of the problem. Solutions are likely therefore to be very expensive. However, attempts to address salinity issues, such as tree-planting, will have the effect of reducing excessive inundation of these wetlands.

Wetlands of the Swan Coastal Plain (general) Wetlands of the Swan Coastal Plain are potentially affected by excessive groundwater extraction. The reduction of evapotranspiration associated with clearing for urbanisation however mitigates the effect of groundwater extraction. As the increased exploitation of surface water is associated with other environmental costs, an increase in Perth’s population without a

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reduction in per capita water usage will negatively impact these wetlands. There is however a relatively large knowledge base regarding the water requirements of wetland vegetation and aquatic invertebrates and the hydrology of these wetlands due to a targeted research program carried out in the late 1980s and early 1990s (Kite et al., 1994). A large percentage of these wetlands have already been lost through filling and draining for urban development.

Twin Swamps (Swan Coastal Plain, groundwater fed) Opportunities for managing individual wetlands of the Swan Coastal Plain are similar to those for small riverine wetlands. The water regime of Twin Swamps is managed to meet the requirements of the endangered western swamp turtle (Pseudemydura umbrina). Groundwater is pumped into Twin Swamps to extend the hydroperiod. This approach will no longer work if the groundwater table falls too far.

Desert soaks and gnamma holes of Western Australia with water regimes potentially adversely affected by feral camels The permanent nature of many desert soaks and gnamma holes is threatened by camels. Trampling by camels may damage the vegetation of desert soaks, which could lead to the greater exposure of the water surface, resulting in their drying up (Dragon Tree Soak, ANCA, 1996). Camels drink some gnamma holes dry (Gibson Desert Gnamma Holes, ANCA, 1996). Cost is a limitation to protecting these wetlands from the potentially significant alteration to their water regimes by camels. This could be achieved by either reducing camel numbers or in some cases by the fencing off of small wetlands.

Wetlands of the Australian Alps threatened by alterations to drainage Alpine wetlands are threatened by alterations to drainage caused by walkers (Davies Plain, Kosciusko Alpine Fens, Bogs and Lakes, Mount Buffalo Peatlands, etc), stock (Caledonia Fen) and four-wheel driving (Davies Plain)

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(ANCA, 1996). Limitations to the protection of the water regimes of these wetlands are those associated with the cost of education campaigns, signs, the re-routing of walking tracks, and fences to exclude stock. Hydrological research may be required to determine the extent of the threats to the water regimes of the wetlands.

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Table 18. Limitations and opportunities for implementing environmental water allocations for wetlands.

Region Type of wetland Source of water Nature of threat to Limitations Opportunities Examples wetland water regime These wetlands are generally located in Murray Darling Riverine terminal Surface water Reduced quantity of There is frequently an Lower Gwydir wetlands south-eastern Basin wetlands dominated. water (reduction of over-allocation of Australia, where work Narran Lakes certain flows) due to water for consumptive NSW, Vic, SA, River has been done of abstraction and purposes, and a high Macquarie Marshes Qld wetland plant water regulation demand for water for requirements. irrigated agriculture. Great Cumbung Swamp Increased permanency Many of these in parts (eg near Environmental water wetlands have irrigation channels). allocations to wetlands management plans are associated with with environmental economic costs to water allocations. irrigators. Many sites are Ramsar- Lack of data regarding listed (eg Lower pre-disturbance water Gwydir wetlands, regime. Narran Lakes). Legal limits to the Environmental water delivery of large allocations to wetlands floods are associated with Political boundaries economic benefits to rarely coincide with graziers. catchment boundaries, The existence of the making management Murray-Darling Basin difficult. eg the Narran Commission should Lakes of NSW: facilitate coordination significant upstream of management. extraction occurs Queensland.

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Region Type of wetland Source of water Nature of threat to Limitations Opportunities Examples wetland water regime A methodology has been developed for the Murray Darling Floodplain Surface water Reduced quantity of River regulation, Barmah-Millewa Forest determination of plant Basin wetlands of SE dominated. water (reduction of diversion, abstraction, water requirements for Australia certain flows) flood mitigation NSW, Vic, SA, these wetlands Qld Legal limits to the (Roberts et al., 2000). River (bank delivery of large overflow). Increased permanency In the case of the floods in parts. Barmah-Millewa In the case of the Forest, the stakeholders Increased water in Barmah-Millewa are represented through summer threatens Forest, difficulties the Barmah-Millewa moira grass plains of associated with its Forum, making trade- the Barmah-Millewa location on the offs potentially easier. Forest (Atkins, 1993) boundary of two The existence of the states (NSW and Murray-Darling Basin Victoria), ie, two Commission should jurisdictions. facilitate coordination of management. Regulators are often present, facilitating Murray Darling Small or isolated Surface water Increased permanency Bool and Hacks Lagoon management of water Basin and riverine wetlands dominated. SA levels. elsewhere affected by Irrigation Lake Woolpolool, irrigation There is some drainage water, Chowilla floodplain SA drainage water, information regarding or water from or river the water requirements regulated regulation. of species adversely streams. affected by excessive inundation (Denton & Ganf, 1994)

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Region Type of wetland Source of water Nature of threat to Limitations Opportunities Examples wetland water regime

Great Artesian Artesian springs Artesian water Aquifer drawdown Aquifer flow in the The Great Artesian Elizabeth Springs Basin (NSW, due to extraction from Great Artesian Basin Basin Project is a Aramac Springs QLD, SA) bores. crosses State political joint Federal and boundaries (Qld, State Government Lake Eyre Mound Springs

NSW, SA) initiative Boggomoss Springs Artesian pressure and (Queensland Improvements in discharge rates have Department of artesian pressure declined (Queensland Natural Resources resulting from the Department of web site) Great Artesian Basin Natural Resources Project could be There are web site) slow. Before they are opportunities for achieved some reducing water springs could become wastage (the Great extinct, along with Artesian Basin any endemic fauna, Rehabilitation ie, response time or Project). lag. Preservation of the resource for consumptive use by

reducing wastage does not conflict with conservation values.

ENVIRONMENTAL WATER REQUIREMENTS FOR WETLANDS 161 5. OPPORTUNITIES AND LIMITATIONS

Region Type of wetland Source of water Nature of threat to Limitations Opportunities Examples wetland water regime

Queensland coast Wetlands of the Various; riverine Alterations to wetland Conflicts between Herbert River Floodplain (Wet Tropics) Wet Tropics plus local hydrology due to conservation values wetlands impacted by catchment run- drainage from and agricultural Innisfail area wetlands alterations to off adjacent agricultural practices (drainage) drainage land. Russell River wetlands There are no Ramsar- associated with listed sites agriculture Tully River/Murray River Floodplains (especially Drainage of wetlands sugarcane for agriculture. Wyvuri Swamp production) Conflicts between conservation values Tasmania Wetlands as above Lake water levels Little Waterhouse Lake and agricultural and impacted by affected by water use pastoral values/uses Logan Lagoon alterations to for agriculture (Little drainage Waterhouse Lake) associated with

agriculture Logan Lagoon is threatened by drainage for the purpose of improving soil drainage on nearby pasture Pressure on the water There has been a resource for town large amount of Western Subterranean Groundwater Reduced flow due to Cape Range subterranean water supply research interest in Australia karst wetlands groundwater wetlands the endemic cave extraction fauna

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Region Type of wetland Source of water Nature of threat to Limitations Opportunities Examples wetland water regime

Western Wetlands of the Groundwater Excessive inundation The problem is large- Pumping Lake Toolibin Australia WA wheatbelt due to rising water scale in nature. Planting deep rooted Coyrecup Lake table related to Solutions are likely to perennial vegetation in clearing of native be large-scale and Yealering Lakes System strategic locations vegetation expensive Efforts to address salinity issues will also ameliorate excessive inundation

Western Wetlands of the Groundwater Reduced water levels Threats to wetland The hydrologic effect Gnangara mound lakes Australia Swan Coastal and alterations in water regimes of groundwater Jandakot mound lakes Plain (general) variability associated (abstraction for abstraction (lowering (these include the Ramsar with groundwater Perth’s water supply of the water table) sites Thomsons Lake and abstraction and hydrologic mitigates against the Forrestdale Lake) alterations resulting hydrological effect of

from clearing) are clearing (rising water Increased levels likely to increase with table). associated with increasing population. Potential water-saving effects of clearing. The alternative to opportunities may groundwater exist. abstraction, increased A knowledge-base exploitation of surface exists regarding water resources, also ecological response to has environmental water regime due to a costs. targeted research program carried out in the early 1990s based on wetlands of the Gnangara Mound

ENVIRONMENTAL WATER REQUIREMENTS FOR WETLANDS 163 5. OPPORTUNITIES AND LIMITATIONS

Region Type of wetland Source of water Nature of threat to Limitations Opportunities Examples wetland water regime

Western Groundwater-fed Groundwater Hydroperiod (period of The solution The hydroperiod was Twin Swamps Australia inundation) in some (pumping able to be extended years was too brief to groundwater into the by pumping in Twin Swamps enable the endangered wetland) will not be groundwater. (Swan Coastal western swamp turtle successful if the Plain) (Pseudemydura groundwater table umbrina) to survive and falls significantly reproduce. The wetland is relatively small (5 ha Desert Desert soak and Groundwater Camels damage Cost of excluding Dragon Tree Soak total, 1 ha main water east/north-east surrounding vegetation. This could camels or reducing area) so fencing may Western permanent potentially lead to the camel population be an option Australia swamp exposure and consequent drying out Reducing camel of the wetland numbers may benefit other ecosystems

Gnamma holes Surface run-off Camels occasionally Cost of excluding Reducing camel Gibson Desert Gnamma drink gnamma holes camels or reducing numbers may benefit Holes dry camel population other ecosystems Australian Alps Bogs, wet heath, Snow melt, direct Trampling by walkers Cost of education, Education campaigns Caledonia Fen, Davies (ACT, NSW, lakes, fens precipitation, and stock, and 4-wheel fencing, signs Plain, Kosciusko Alpine Vic) groundwater driving may result in fens, bogs and lakes, (springs) the alteration of Mount Buffalo Peatlands, drainage lines Rock Flats

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REFERENCES

REFERENCES

Adam, P. (1997) Issues in wetland management. Wetlands in a Dry Land: Understanding for Management. p.49-58 Environment Australia, Albury, NSW.

Adam, P. (1999). Wetlands and Ramsar- ecological issues. Water: Wet or Dry? The Proceedings of the Water and Wetlands Management Conference. p.63-74. Nature Conservation Council of NSW, St Leonards, NSW

Allan, A. and S. Lovett (1997). Impediments to managing environmental water provisions. Bureau of Resource Sciences, Canberra.

ANCA (1996). A Directory of Important Wetlands in Australia. Australian Nature Conservation Agency, Canberra. (www.ea.gov.au/wetlands)

Arthington, A.H. (1998). Comparative evaluation of environmental flow assessment techniques: Review of holistic methodologies. Report OP 26/98. Land and Water Resources Research and Development Corporation, Canberra.

Arthington, A.H. and B.J. Pusey (1992). In-stream flow management in Australia: methods, deficiencies and future directions. Water. An Endangered National Resource. p.52-60. Australian Institute of Biology Inc., Fortitude Valley, Queensland.

Arthington, A.H., S.O. Brizga and M.J. Kennard (1998). Comparative evaluation of environmental flow assessment techniques: best practice framework. Report OP 25/98. Land and Water Resources Research and Development Corporation, Canberra.

Arnold, J.M. (1990). Jenny Arnold's Wetlands Resource Book Bulletin 266. Environmental Protection Authority, Perth.

Atkins, B. (1993). Final Project Report: the Integrated Watering Strategy for Mid-Murray Wetlands (IWS) Integrated Report Strategy Report No. 2,

ENVIRONMENTAL WATER REQUIREMENTS FOR WETLANDS 167

Floodplain Ecology Group, Department of Conservation and Natural Resources, Shepparton.

Bacon, P., K. Ward, P. Craven, B. Bone, M. Harper, M. Maher, H. Tane and S. Briggs (1994). Floodplain Land Use Issues in the Murray-Darling Basin. Murray-Darling Basin Floodplain Wetlands Management Workshop- Discussion Papers, 20-22 October, 1992, Albury. Cited In Keyte (1994)

Bailey, M.C. and Hamilton, D.P. (1997). The effect of wind speed and light on phytoplankton distribution in a shallow lake. Internationale Vereinigung fur theoretische und angewandte Limnologie 26: 436-440.

Balla, S.A. (1994). Wetlands of the Swan Coastal Plain. Volume 1. Their Nature and Management. Water Corporation of Western Australia and Western Australia Department of Environmental Protection, Perth.

Balla, S.A. and J.A. Davis (1993). Wetlands of the Swan Coastal Plain. Volume 5. Managing Perth's Wetlands to Conserve the Aquatic Fauna. Water Corporation of Western Australia and Western Australia Department of Environmental Protection, Perth.

Barmah-Millewa Forum and MDBC (2000). The Barmah-Millewa Forest Water Management Strategy April, 2000. The Barmah-Millewa Forum and the Murray-Darling Basin Commission. Accessed from http://www.mdbc.gov.au April, 2000.

Beck, R.G. (1985). Field observations upon the Dwarf Galaxiid Galaxiella pusilla (Mack) (Pisces: Galaxiidae). South Australian Naturalist 60: 12-22. Cited in Koehn and O'Connor, (1990).

Bennett, M. and R. McCosker (1994). Estimating environmental flow requirements of wetlands. Environmental Flows Seminar 1994, Australian Water and Wastewater Association, Canberra.

Blanch, S. (2000). Secret carp business- exposed! Carp management options through new research. New carp project in Barmah Forest Inland Rivers Network News. May 2000 pp.12-13. www.irnnsw.org.au

168 ENVIRONMENTAL WATER REQUIREMENTS FOR WETLANDS

REFERENCES

Boulton, A.J. and M.A. Brock (1999). Australian Freshwater Ecology. Processes and Management. Gleneagles, Glen Osmond S.A.

Braithwaite, L.W. and H.J. Frith (1968). Waterfowl in an inland swamp in New South Wales III. Breeding. CSIRO Wildlife Research 14: 65-109.

Bren, L.J. (1992). Tree invasion of an intermittent wetland in relation to changes in the flooding frequency of the River Murray, Australia. Australian Journal of Ecology 17: 395-408.

Brereton, G.J. (1994). The impact of river regulation on flooding and erosion in the Macquarie Marshes. Macquarie Marshes Workshop, pp.87-91. Macquarie Marshes Total Catchment Management Subcommittee, NSW Department of Water Resources.

Briggs, S.V. and W.G. Lawler (1989). Management of Murray-Darling wetlands for waterbirds. In Conservation in Management of the River Murray System- Making Conservation Count. Third Fenner Conference on the Environment, Australian Academy of Science, Canberra

Briggs, S.V. and S.A. Thornton (1999). Management of water regimes in River Red Gum Eucalyptus camaldulensis wetlands for waterbird breeding. Australian Zoologist 31(1): 187-197.

Briggs, S.V., S.A. Thornton and W.G. Lawler (1994). Management of red gum wetlands for waterbirds. Report on Project N108 of the Natural Resources Management Strategy, Murray Darling Basin Commission. Cited in Scott (1997).

Brock, M.A. (1998). Are temporary wetlands resilient? Evidence from seed banks of Australian and South African wetlands. Wetlands for the Future. p.193-206. Proceedings of INTECOL's V International Wetlands Conference. Gleneagles Press, Adelaide.

Brock, M.A. (1999). Are aquatic seed banks resilient to water regime alteration? Implications for the Paroo River system. A Free-Flowing River: the Ecology of the Paroo River. Kingsford, R.T. (ed.) pp.129-137. NSW Parks and Wildlife Service, Hurstville, NSW.

ENVIRONMENTAL WATER REQUIREMENTS FOR WETLANDS 169

Brock, M.A. and M.T. Casanova (1997). Plant life at the edge of wetlands: ecological responses to wetting and drying patterns. Frontiers in Ecology: Building the Links, pp.181-192. Elsevier, Oxford.

Brock, P. (1996). Grazier and irrigator perceptions of management issues affecting the Macquarie Marshes. Australian Journal of Soil and Water Conservation 9(2): 9-15.

Brock, P.M. (1998). The significance of the physical environment of the Macquarie Marshes. Australian Geographer 29(1): 71-90.

Brownlow, M.D., A.D. Sparrow and G.G. Ganf (1994). Classification of water regimes in systems of fluctuating water level. Australian Journal of Marine and Freshwater Research 45(8): 1375-1385.

Bunn, S.E. (1999). The challenges of sustainable water use and wetland management. Water: Wet or Dry? The Proceedings of the Water and Wetlands Management Conference, Nature Conservation Council of NSW, St Leonards, NSW.

Burbidge, A.A. and G. Kuchling (1994). Western Swamp Tortoise Recovery Plan. Report No. 11, Department of Conservation and Land Management. Perth.

Burgess, G.K. and T.L. Vanderbyl (1996). Habitat Analysis Method for determining environmental flow requirements. Water and the Environment. 23rd Hydrology and Water Resources Symposium, Hobart, Tasmania, Institution of Engineers, Australia.

Bush, B., B. Maryan, R. Browne-Cooper, and D. Robinson, (1995). A Guide to the Reptiles and Frogs of the Perth Region. University of Western Australia Press, Nedlands, WA.

Cargeeg, G.C., G.N. Boughton, L.R. Townley, G.R. Smith, S.J. Appleyard and R.A. Smith (1987). Perth Urban Water Balance Study. Volume 1. Findings Water Authority of Western Australia, Leederville WA.

170 ENVIRONMENTAL WATER REQUIREMENTS FOR WETLANDS

REFERENCES

Carter, V. (1986). An overview of the hydrologic concerns related to wetlands in the United States. Canadian Journal of Botany 64: 367-374.

Chambers, J.M., N.L. Fletcher and A.J. McComb (1995). A Guide to the Emergent Wetland Plants of South-Western Australia The Marine and Freshwater Research Laboratory, Murdoch University, Murdoch, Western Australia.

Chapman, M.G. and A.J. Underwood (1997). Concepts and issues in restoration of mangrove forests in urban environments. Frontiers in Ecology: Building the Links. Oxford, p.103-114. Elsevier, Oxford.

Clay, B.T. (1981). Observations on the breeding biology and behaviour of the long-necked tortoise (Chelodina oblonga). Journal of the Royal Society of Western Australia 64: 27-32.

Cogger, H.G. (1996). Reptiles and Amphibians of Australia. Reed, Melbourne.

Craig, A., K.F. Walker and A.J. Boulton (1991). Effects of edaphic factors and flood frequency on the abundance of lignum (Muehlenbeckia florulenta Meissner) (Polygonaceae) on the River Murray Floodplain, South Australia. Australian Journal of Botany 39: 431-443.

Crome, F.H.J. (1986). Australian waterfowl do not necessarily breed on a rising water level. Australian Wildlife Research 13: 461-480.

Crome, F.H.J. (1988). To drain or not to drain? Intermittent swamp drainage and waterbird breeding. 88: 243-248.

Crook, I.G. and T. Evans (1981). Thomsons Lake Nature Reserve Department of Fisheries and Wildlife, Perth.

Davis, J.A. and R. Froend (1999). Loss and degradation of wetlands in southwestern Australia: underlying causes, consequences and solutions. Wetlands Ecology and Management 7(1-2): 13-23.

ENVIRONMENTAL WATER REQUIREMENTS FOR WETLANDS 171

Davis, J.A., R.S. Rosich, J.S Bradley, J.E. Growns, L.G. Schmidt and F. Cheal (1993). Wetlands of the Swan Coastal Plain Volume 6. on the Basis of Water Quality and Invertebrate Community Data. Water Corporation of Western Australia and Western Australia Department of Environmental Protection. Perth.

DCE (1983). Conservation Reserves for Western Australia as recommended by the Environmental Protection Authority 1983. The Darling System - System 6. Part II: Recommendations for Specific Localities. Western Australian Department of Conservation and Environment, Western Australia. Report No.13.

DCE (1992). Lower Snowy River Wetlands Proposed Management Plan. Department of Conservation and Environment, Orbost Region, National Parks Division.

DCNR (1990). Draft Hird and Johnson Swamps Interim Management Statement. Unpublished Report. Department of Conservation and Natural Resources, Bendigo Region, Victoria.

Denham, R.E. and T. McAuliffe (1994). Environmental flow management in regulated rivers: a case study of the Lachlan Valley. Proceedings of the Environmental Flows Seminar pp.87-94, AWWA (Australian Water and Wastewater Association), Artarmon, NSW.

DLWC and NPWS (1996). Macquarie Marshes Water Management Plan. NSW Department of Land and Water Conservation and National Parks and Wildlife Service.

DLWC (1998). Lachlan Catchment State of the Rivers Report 1997. NSW Department of Land and Water Conservation.

Debus, S. (1989). Moree Watercourse. RAOU Newsletter 81: 5. Cited in Keyte (1994)

Denton, M. and G.G. Ganf (1994). Response of juvenile Melaleuca halmaturorum to flooding: management implications for a seasonal wetland, Bool Lagoon, South Australia. Australian Journal of Marine and Freshwater Research 45(8): 1395-1408.

172 ENVIRONMENTAL WATER REQUIREMENTS FOR WETLANDS

REFERENCES

EPA (1990). Thomson Lake Urban Development Revised South Jandakot Drainage Management Plan. Ministerial Condition 2. Bulletin No. 429. Environmental Protection Authority, Perth.

EPA (1996). Gnangara Mound groundwater resources. Water and Rivers Commission Proposed Changes to Environmental Conditions. Environmental Protection Authority, Perth.

Frith, H.J. (1957). Breeding and movements of wild ducks in inland New South Wales. CSIRO Wildlife Research 2: 17-31.

Froend, R. H., R.C.C. Farrell, C.F. Wilkins, C.C. Winson, and A.J. McComb (1993). Wetlands of the Swan Coastal Plain. Volume 4. The Effect of Altered Water Regimes on Wetland Plants. Water Authority of Western Australia, Perth.

Gippel (1993). Hydrological management of a lake with floating islands near Pirron Lake, Victoria, Australia. Journal of Environmental Management 37: 219-238

Gippel, C.J. (1996). Water Management Manual of Wetlands Management Wetlands Conservation Report Series No. 4, pp.101-152. National Parks Service and Department of Natural Resources and Environment, East Melbourne, Victoria.

Growns, I.O. (1998). Methods addressing the flow requirements of aquatic invertebrates. In Arthington, A.H. and J.M. Zalucki (eds), Comparative Evaluation of Environmental Flow Assessment Techniques: Review of Methods. p.115-136. Land and Water Resources Research and Development Corporation, Canberra.

Halse, S.A., G.B. Pearson, and S. Patrick (1993). Vegetation of depth-gauged wetlands in nature reserves of south-west Western Australia. Technical Report No. 30, Department of Conservation and Land Management, Perth.

ENVIRONMENTAL WATER REQUIREMENTS FOR WETLANDS 173

Hamilton-Smith, E., K. Kiernan and A. Spate (1998). Karst Management Considerations for the Cape Range Province Western Australia. Report for the Western Australian Department of Environmental Protection.

Hatton, T. and R. Evans (1998). Dependence of ecosystems on groundwater and its significance to Australia. Land and Water Resources Research and Development Corporation Report No.OP 12/98.

Hydro Technology (1995). An Environmental Water Management Strategy for the Kerang Lakes. February, 1995. Report prepared by Hydro Technology for the Department of Conservation and Natural Resources, Victoria.

Jackson, P.D. (1992). The of Australian freshwater : the Fish Action Plan. Water. An Endangered National Resource. Australian Institute of Biology Inc. pp. 61-66. Fortitude Valley, Queensland.

Jensen, A. (1994). Flow Management in the Lower Murray. Proceedings of the Environmental Flows Seminar pp. 125-133, AWWA (Australian Water and Wastewater Association), Artarmon, NSW.

Jensen, A., C. Nicolson and J. Carter (1994). Preservation and management of natural wetlands in the South Australian Murray Valley. Water Science and Technology 29(4): 325-333.

Jensen, A., J. Zwar and D. Niejalke (1998). Protecting oases in the desert: responsible use of precious water resources from the Great Artesian Basin. Wetlands for the Future. INTECOL's V International Wetlands Conference. pp 109-120. Gleneagles Press, Adelaide.

Keyte, P. A. (1994). Lower Gwydir Wetland Plan of Management- 1994-1997. Report for the Lower Gwydir Wetland Steering Committee, Sydney.

Kingsford, R.T. (2000). Ecological impacts of dams, water diversions and river management on floodplain wetlands in Australia. Austral Ecology 25: 109-127.

Kingsford, R.T. and R.F. Thomas (1995). The Macquarie Marshes in arid Australia and their waterbirds: a 50-year history of decline. Environmental Management 19(6): 867-878.

174 ENVIRONMENTAL WATER REQUIREMENTS FOR WETLANDS

REFERENCES

Kingsford, R.T. and W. Johnson (1999). The impact of water diversions on colonially nesting waterbirds in the Macquarie Marshes in arid Australia. Colonial Waterbirds 21: 159-170. Cited in Kingsford (2000).

Kinhill Engineers (1988). Techniques for determining environmental water requirements: a review. Department of Water Resources, Technical Report Series No. 40.Victoria.

Kite, J.M., H.B. Ventriss and N.J. Arrowsmith (1994). Environmental water provisions for groundwater fed ecosystems in Western Australia. Environmental Flows Seminar 1994. p.142-148. Australian Water and Wastewater Association, Canberra,

Knights, P. and B. Fitzgerald (1994). A pragmatic approach to environmental flow management. Environmental Flows Seminar, Australian Water and Wastewater Association, Canberra.

Koehn, J.D. and W.G. O'Connor (1990). Biological Information for Management of Native Freshwater Fish in Victoria. Freshwater Fish Management Branch, Arthur Rylah Institute for Environmental Research, Department of Conservation and Environment, Victoria.

LaBaugh, J.W. (1986). Wetland studies from a hydrologic perspective. Water Resources Bulletin 22: 1-10.

Leitch, C. (1989). Towards a Strategy for Managing the Flooding of Barmah Forest. Department of Conservation, Forests and Lands, Benalla Region.

Lugg, A., S. , G. Fleming and T. O'Donnell (1989). Conservation Value or the Wetlands in the Kerang Lakes Area Report to the Kerang Lakes Area Working Group. October, 1989. Kerang Lakes Assessment Group, Department of Conservation, Forests and Lands.

LWRRDC (1997a). Restoring wetlands connected to regulated rivers. In Wetland research. Restoring the balance. p.18 Land and Water Resources Research and Development Corporation.

ENVIRONMENTAL WATER REQUIREMENTS FOR WETLANDS 175

LWRRDC (1997b). Effects of water-levels on aquatic plants. Wetland research. Restoring the balance. pp.4-5. Land and Water Resources Research and Development Corporation.

Marchant, S. and Higgins, P.J. (1990). Handbook of Australian, New Zealand and Antarctic Birds, Volume 1. Ratites to Ducks. Oxford University Press, Melbourne.

McCosker, R.O. (1998). Methods addressing the flow requirements of wetland, riparian and floodplain vegetation. In Arthington, A.H. and J.M. Zalucki (eds), Comparative Evaluation of Environmental Flow Assessment Techniques: Review of Methods. p.47-65. Land and Water Resources Research and Development Corporation, Canberra.

McCosker, R.O. and J.A. Duggin (1993). Gingham Watercourse Management Plan. Final Report. Department of Ecosystem Management, Unpublished Report University of New England, Armidale.

MDBC (1990). Barmah and Millewa Forests Water Management Plan Information Brochure, Murray-Darling Basin Commission, Canberra.

Mitchell, D.S. (1999). The interdependence of adaptive management and environmental monitoring. Water: Wet or Dry? Proceedings of the Water and Wetlands Management Conference. p.149-154. Nature Conservation Council of NSW, St Leonards, NSW.

Morrison, M.D. (1999). The social benefits and costs of irrigation: an economic perspective. A Free Flowing River: the ecology of the Paroo River. Kingsford, R.T. (ed.) pp.243-256. NSW Parks and Wildlife Service, Hurstville, NSW.

Mudgway, L.B., G.K. Linke and L.T. Huynh (1996). Water for Wetlands. Water for the Environment. pp. 202-207. 23rd Hydrology and Water Resources Symposium, Institution of Engineers, Hobart, Tasmania.

Nickson, A. (1999). Ground-breaking agreement marks new era in Australian wetlands conservation. Wildlife News January-May 1999 86:7.

176 ENVIRONMENTAL WATER REQUIREMENTS FOR WETLANDS

REFERENCES

Pitcher, J. (2000). Modelling biological response to environmental variables in wetlands PhD Thesis, Murdoch University.

Pusey, B.J. (1998). Methods addressing the flow requirements of fish. In Arthington, A.H. and J.M. Zalucki (eds), Comparative Evaluation of Environmental Flow Assessment Techniques: Review of Methods. p.66-105. Land and Water Resources Research and Development Corporation, Canberra.

Rankine and Hill Pty Ltd (1979). Southern Macquarie Marshes Water Management Works, Environmental Impact Statement. Report prepared for Water Resources Commission, Sydney. Cited in Keyte (1994).

Rea, N. (1992). The influence of water regime on the population ecology of two emergent macrophytes in South Australia. PhD. Thesis, University of Adelaide, Adelaide. Cited in Denton and Ganf (1994).

Reyenga, P.J., M.A. Habermehl and S.M. Howden (1998). The Great Artesian Basin-Bore rehabilitation, and groundwater management. Bureau of Resource Sciences, Canberra.

Richardson, B.A. (1986). Evaluation of instream flow methodologies for freshwater fish in New South Wales. Stream Protection. The Management of Rivers for Instream Uses. pp. 143-167. Water Studies Centre, Chisholm Institute of Technology, East Caulfield.

Roberts, J., W. J. Young and F. Marston (2000). Estimating the water requirements for plants of floodplain wetlands: A guide. CSIRO Land and Water, Report No. 99/60, Canberra.

Roberts, J.D. and A.R. Main (1993). Frogs and Wetlands on the Swan Coastal Plain. Unpublished report, Zoology Department, University of Western Australia. Cited in Wilkins (1993).

Schofield, N. (1998). The Ord Development: a multiplicity of management challenges. Rivers for the Future 6: 6-11

ENVIRONMENTAL WATER REQUIREMENTS FOR WETLANDS 177

Scott, A. (1997). Relationships between waterbird ecology and river flows in the Murray-Darling Basin. CSIRO Land and Water. Report No.5/97. Accessed from http://www.dwr.csiro.au January 2000.

Scott, A. and T. Grant (1997). Impacts of water management in the Murray- Darling Basin on the platypus (Ornithorhynchus anatinus) and the water rat (Hydromys chrysogaster). CSIRO Land and Water Report No.23/97. Accessed from http://www.dwr.csiro.au January 2000.

Seymour, R. and J. Roberts (1991). Embryonic respiration and oxygen distribution in foamy and non-foamy egg masses of the frog Limnodynastes tasmaniensis. Physiological Zoology 64: 1322-1340.

Shaikh, M., A.T. Brady and P. Sharma (1996). Applications of remote sensing to assess wetland inundation and vegetation response in relation to hydrology in the Great Cumbung Swamp, Lachlan Valley, NSW, Australia. Wetlands for the Future. INTECOL's V International Wetlands Conference. pp 595-605. Gleneagles Press, Adelaide.

Shields, J. (1998). Murrumbidgee environmental flows: the first year. Water: Wet or Dry? The Proceedings of the Water and Wetlands Management Conference St Leonards, NSW, Nature Conservation Council of NSW.

Simpson, K. and N. Day (1993). Field Guide to the Birds of Australia. Viking. Ringwood, Victoria,

Storey, A.W., R.M. Vervest, G.B. Pearson and S.A. Halse (1993). Wetlands of the Swan Coastal Plain. Volume 7. Waterbird Usage of Wetlands on the Swan Coastal Plain. Water Corporation of Western Australia and Western Australia Department of Environmental Protection, Perth.

Swales, S. and J.H. Harris (1995). The expert panel assessment method (EPAM): a new tool for determining environmental flows in regulated rivers. The Ecological Basis for River Management. New York., Wiley. 125-146.

Taylor, P.J., G.R. Walker, Hodgson, G., Hatton, T.J. and R.L. Correll (1996). Testing of a GIS model of Eucalyptus largiflorens health on a semi-arid, saline floodplain. Environmental Management 20(4): 553-564.

178 ENVIRONMENTAL WATER REQUIREMENTS FOR WETLANDS

REFERENCES

Timms, B.V. (1997). Spatial and temporal variation in inundation of wetlands in the Paroo catchment of the Murray-Darling. Wetlands in a Dry Land: Understanding for Management, Albury, NSW, Environment Australia.

Townley, L.R., J.V. Turner, A.D. Barr, M.G. Trefry, K.D. Wright, V. Gailitis., C.J. Harris and C.D. Johnston (1993). Wetlands of the Swan Coastal Plain. Volume 3. Interaction between Lakes, Wetlands and Unconfined Aquifers. Water Authority of Western Australia, Perth.

Tranter, D. (1999). Case study: Wingecarribee Swamp. Water: Wet or Dry? Proceedings of the Water and Wetlands Management Conference, Nature Conservation Council of NSW, St Leonards, NSW.

WAMP (1999). Water Management (Cooper Creek) Plan 1999. Draft Water Resources Act. .

WAWA (1992). Environmental Management Programme, Jandakot Groundwater Scheme Stage 2. Water Authority of Western Australia, Perth.

WAWA (1995) Review of Proposed Changes to Environmental Conditions. Gnangara Mound Groundwater Resources. Section 46. Water Authority of Western Australia, Perth.

Wilkins, C. (1993). Ecological considerations for the artificial maintenance of Lake Banganup water-levels (Jandakot WA). Honours thesis, Murdoch University, Perth.

Young, W. (1999). Making decisions on environmental flows. In Boulton, A.J. and Brock, M.A. Australian Freshwater Ecology. Processes and Management Box 10.11 p.190. Gleneagles, Glen Osmond,jk SA.

Young, W.D., S.M. Cuddy, F.M. Marston and T.F.N. Farley (1999) Environmental Flows Decision Support System. CSIRO Land and Water. Accessed from http://www.dwr.csiro.au. November 1999.

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WEB SITES AND CONTACTS

WEB SITES

Directory of Important Wetlands www.ea.gov.au/wetlands Accessed April 2000

Ramsar http://ramsar.org Accessed April 2000

Queensland Department of Natural Resources How is artesian water being conserved? http://www.dnr.qld.gov.au/resourcenet/water/artesian-basin/conservation.html Accessed January 2000

PERSONAL CONTACTS

Alisa Krasnostein Masters Student Centre for Water Research University of Western Australia

Rod Smith Birds Australia Western Australian Group Phone (08) 9383 7749

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